How to recover a lost partition in Linux

Partition tables define how your disks are divided into distinct partitions. Each partition must be formatted with a filesystem (e.g., ext4, exFAT, NTFS) before usage.

When a partition is deleted, only its entry in the partition table is removed, leaving the filesystem itself intact. By scanning the disk for existing filesystems and rebuilding the partition table based on the found filesystems, you can recover deleted or lost partitions.

In Linux, one such partition recovery application is TestDisk. To ensure successful partition recovery, use unmounted filesystems and a live Linux distribution or installer disk (e.g., Ubuntu).

1. Boot your computer using a live Linux distribution or an installer disk such as Ubuntu's.
2. Enter Live CD mode when available if booting from installer disk.

   For Ubuntu installer, click on the Try Ubuntu button.

3. Open the terminal.

   If no Live CD mode available, press <ctrl> + <alt> + <f2> keys to get to the terminal.

4. List and identify the disk containing the deleted or lost partition.

   $ lsblk
   NAME  MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
   loop0   7:0    0  1.9G  1 loop /rofs
   loop1   7:1    0 89.3M  1 loop /snap/core/6673
   loop2   7:2    0 53.7M  1 loop /snap/core18/941
   loop3   7:3    0  151M  1 loop /snap/gnome-3-28-1804/31
   loop4   7:4    0    4M  1 loop /snap/gnome-calculator/406
   loop5   7:5    0 14.8M  1 loop /snap/gnome-characters/254
   loop6   7:6    0 1008K  1 loop /snap/gnome-logs/61
   loop7   7:7    0  3.7M  1 loop /snap/gnome-system-monitor/77
   loop8   7:8    0 35.3M  1 loop /snap/gtk-common-themes/1198
   sda     8:0    0   20G  0 disk
   sr0    11:0    1    2G  0 rom  /cdrom

5. Enable additional repositories if necessary.

   $ sudo add-apt-repository universe
   'universe' distribution component enabled for all sources.
   ##### snipped
6. Install TestDisk using a package installer if it's not pre-installed.

   $ sudo apt install --assume-yes testdisk
   Reading package lists... Done
   Building dependency tree
   Reading state information... Done
   The following NEW packages will be installed:
     testdisk
   0 upgraded, 1 newly installed, 0 to remove and 316 not upgraded.
   Need to get 345 kB of archives.
   ##### snipped

7. Launch testdisk.

   $ sudo testdisk

8. Select No Log with the arrow keys and press [ENTER].
9. Choose the disk with the lost or deleted partition and press [ENTER] to proceed.
10. Select the disk's partition table type and press [ENTER].

    Intel is the most common partition type with EFI GPT starting to gain popularity.

11. Press [ENTER] to start analysing the disk.
12. Press [ENTER] again to search for potential partitions on the chosen disk.
13. Select the found partition and press [ENTER] to continue.
14. Choose Write and press [ENTER] to update the partition table.
15. Press Y to confirm the partition table update.
16. Press [ENTER] on Ok to continue.
17. Select Quit and press [ENTER] to return to disk selection menu.
18. Select Quit and press [ENTER] to exit the program.
19. Verify that the partition table has been recovered.
20. Restart your computer.

    $ sudo reboot