Mounted hard disk is missing

I have been using my Ubuntu 18.04 and I moved to 20.04 some months ago. I used 2 hard disks: one ssd for operating system and one for storage. The storage one was mounted in mnt and it was set to be attached on system load. I have been using without any problem for 2 years. Suddenly today after I switched off my pc, when I start pc again, I see my storage drive is missing.I tried

sudo fdisk -l[sudo] password for johnny: Disk /dev/loop0: 195.8 MiB, 205287424 bytes, 400952 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop1: 195.79 MiB, 205279232 bytes, 400936 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop2: 10.18 MiB, 10670080 bytes, 20840 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop3: 9.9 MiB, 9531392 bytes, 18616 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop4: 99.38 MiB, 104202240 bytes, 203520 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop5: 99.39 MiB, 104210432 bytes, 203536 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop6: 55.43 MiB, 58114048 bytes, 113504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop7: 61.75 MiB, 64729088 bytes, 126424 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/sda: 111.82 GiB, 120040980480 bytes, 234455040 sectorsDisk model: WDC WDS120G2G0A-Units: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: gptDisk identifier: 91269E3D-54B4-4B3A-9B10-C1A2ED932595Device       Start       End   Sectors   Size Type/dev/sda1     2048   1050623   1048576   512M EFI System/dev/sda2  1050624 234452991 233402368 111.3G Linux filesystemDisk /dev/loop8: 55.45 MiB, 58134528 bytes, 113544 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop9: 61.79 MiB, 64770048 bytes, 126504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop10: 140.68 MiB, 147492864 bytes, 288072 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop11: 164.78 MiB, 172761088 bytes, 337424 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop12: 2.51 MiB, 2621440 bytes, 5120 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop13: 219 MiB, 229638144 bytes, 448512 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop14: 2.24 MiB, 2342912 bytes, 4576 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop15: 218.102 MiB, 229629952 bytes, 448496 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop16: 162.89 MiB, 170778624 bytes, 333552 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop17: 140.7 MiB, 147517440 bytes, 288120 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop18: 260.73 MiB, 273375232 bytes, 533936 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop19: 26.24 MiB, 27504640 bytes, 53720 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop20: 295.62 MiB, 309968896 bytes, 605408 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop21: 135.45 MiB, 142016512 bytes, 277376 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop22: 64.79 MiB, 67915776 bytes, 132648 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop23: 295.73 MiB, 310079488 bytes, 605624 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop24: 50.98 MiB, 53432320 bytes, 104360 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop25: 230.63 MiB, 241819648 bytes, 472304 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop26: 139.13 MiB, 145883136 bytes, 284928 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop27: 295.67 MiB, 310018048 bytes, 605504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop28: 26.14 MiB, 27410432 bytes, 53536 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop29: 65.1 MiB, 68259840 bytes, 133320 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytes

I am seeing the system disk

Disk /dev/sda: 111.82 GiB, 120040980480 bytes, 234455040 sectorsDisk model: WDC WDS120G2G0A-

but not the storage disk.How can I solve my problem ?

Update:Mysteriously after 5 hours later when I again start my Ubuntu pc the hard drive has been attached again.

sudo fdisk -l[sudo] password for johnny: Disk /dev/loop0: 195.8 MiB, 205287424 bytes, 400952 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop1: 195.79 MiB, 205279232 bytes, 400936 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop2: 10.18 MiB, 10670080 bytes, 20840 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop3: 9.9 MiB, 9531392 bytes, 18616 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop4: 99.38 MiB, 104202240 bytes, 203520 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop5: 99.39 MiB, 104210432 bytes, 203536 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop6: 55.43 MiB, 58114048 bytes, 113504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop7: 55.45 MiB, 58134528 bytes, 113544 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/sdb: 931.53 GiB, 1000204886016 bytes, 1953525168 sectorsDisk model: WDC WD10EZEX-22MUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 4096 bytesI/O size (minimum/optimal): 4096 bytes / 4096 bytesDisklabel type: dosDisk identifier: 0x0e1e90eaDevice     Boot     Start        End   Sectors   Size Id Type/dev/sdb1            2048  976760831 976758784 465.8G  7 HPFS/NTFS/exFAT/dev/sdb2       976760832 1953519615 976758784 465.8G  7 HPFS/NTFS/exFATDisk /dev/sda: 111.82 GiB, 120040980480 bytes, 234455040 sectorsDisk model: WDC WDS120G2G0A-Units: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: gptDisk identifier: 91269E3D-54B4-4B3A-9B10-C1A2ED932595Device       Start       End   Sectors   Size Type/dev/sda1     2048   1050623   1048576   512M EFI System/dev/sda2  1050624 234452991 233402368 111.3G Linux filesystemDisk /dev/loop8: 61.79 MiB, 64770048 bytes, 126504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop9: 61.75 MiB, 64729088 bytes, 126424 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop10: 140.7 MiB, 147517440 bytes, 288120 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop11: 140.68 MiB, 147492864 bytes, 288072 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop12: 162.89 MiB, 170778624 bytes, 333552 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop13: 164.78 MiB, 172761088 bytes, 337424 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop14: 219 MiB, 229638144 bytes, 448512 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop15: 218.102 MiB, 229629952 bytes, 448496 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop16: 2.51 MiB, 2621440 bytes, 5120 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop17: 64.79 MiB, 67915776 bytes, 132648 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop18: 26.14 MiB, 27410432 bytes, 53536 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop19: 2.24 MiB, 2342912 bytes, 4576 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop20: 139.13 MiB, 145883136 bytes, 284928 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop21: 260.73 MiB, 273375232 bytes, 533936 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop22: 65.1 MiB, 68259840 bytes, 133320 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop23: 230.63 MiB, 241819648 bytes, 472304 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop24: 26.24 MiB, 27504640 bytes, 53720 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop25: 295.62 MiB, 309968896 bytes, 605408 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop26: 135.45 MiB, 142016512 bytes, 277376 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop27: 295.67 MiB, 310018048 bytes, 605504 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop28: 50.98 MiB, 53432320 bytes, 104360 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/loop29: 295.73 MiB, 310079488 bytes, 605624 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesjohnny@johnny-B250M-HD3:~$ 

The fstab

# /etc/fstab: static file system information.## Use 'blkid' to print the universally unique identifier for a# device; this may be used with UUID= as a more robust way to name devices# that works even if disks are added and removed. See fstab(5).## <file system> <mount point>   <type>  <options>       <dump>  <pass># / was on /dev/sda2 during installationUUID=58e2813b-339e-4b0a-9003-ac8833ee9a62 /               ext4    errors=remoun># /boot/efi was on /dev/sda1 during installationUUID=49EE-E626  /boot/efi       vfat    umask=0077      0       1/swapfile                                 none            swap    sw           >/dev/disk/by-uuid/CCA2B0E3A2B0D2E6 /mnt/storage auto nosuid,nodev,nofail,x-gvfs>/dev/disk/by-uuid/4CCCAD05CCACEB02 /mnt/important auto nosuid,nodev,nofail,x-gv>