I have ubuntu 18.04 installed on a system(single os, no dual boot) which refused to boot after I had to do a hard restart and sent me to the grub_rescue prompt.
ls on grub_rescue prompt lists (hd0) (hd0,msdos7) (hd0,msdos6) (hd0,msdos5) (hd0,msdos3) (hd0,msdos1) of which (hd0,msdos7) and (hd0,msdos1) were ext2 and others were unknown filesystem.
I tried setting the path and prefix, etc as suggested in solutions I found on this and other forums which doesn't fix the issue and now doing ls on grub_rescue shows me just (hd0) (hd0,msdos7) and now I can not see my partitions even in fdisk -l.
Running boot repair on live session gives me the following:

boot-repair-4ppa203                                              [20230427_1339]

============================== Boot Info Summary ===============================

 => No known boot loader is installed in the MBR of /dev/sda.

sdb: ___________________________________________________________________________

    File system:       iso9660
    Boot sector type:  Unknown
    Boot sector info: 
    Operating System:  
    Boot files:        /boot/grub/grub.cfg

================================ 0 OS detected =================================

================================ Host/Hardware =================================

CPU architecture: 64-bit
Video: Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller from Intel Corporation
Live-session OS is Ubuntu 64-bit (Ubuntu 18.04.6 LTS, bionic, x86_64)

===================================== UEFI =====================================

BIOS/UEFI firmware: 4.6.5 from American Megatrends Inc.
This live-session is in Legacy/BIOS/CSM mode (not in EFI mode).

============================= Drive/Partition Info =============================

Disks info: ____________________________________________________________________

Partitions info (1/3): _________________________________________________________

Partitions info (2/3): _________________________________________________________

Partitions info (3/3): _________________________________________________________

fdisk -l (filtered): ___________________________________________________________

Disk sdb: 28.7 GiB, 30752000000 bytes, 60062500 sectors
Disk identifier: 0x4c050c47
      Boot   Start     End Sectors  Size Id Type
sdb1  *          0 4910399 4910400  2.3G  0 Empty
sdb2       4840192 4844991    4800  2.4M ef EFI (FAT-12/16/32)

parted -lm (filtered): _________________________________________________________

sda:500GB:scsi:512:4096:unknown:ATA ST500DM002-1BD14:;
sdb:30.8GB:scsi:512:512:unknown:SanDisk Ultra:;

blkid (filtered): ______________________________________________________________

NAME   FSTYPE   UUID                                 PARTUUID                             LABEL                    PARTLABEL
├─sda5 swap     b86ba29a-dd33-44f6-878d-9d2f507ff74d                                                               
sdb    iso9660  2021-09-15-20-41-59-00                                                    Ubuntu 18.04.6 LTS amd64 
├─sdb1 iso9660  2021-09-15-20-41-59-00               4c050c47-01                          Ubuntu 18.04.6 LTS amd64 
└─sdb2 vfat     7E74-30B0                            4c050c47-02                          Ubuntu 18.04.6 LTS amd64 

Mount points (filtered): _______________________________________________________

                       Avail Use% Mounted on
/dev/sdb                   0 100% /cdrom

Mount options (filtered): ______________________________________________________

====================== sdb/boot/grub/grub.cfg (filtered) =======================

Try Ubuntu without installing
Install Ubuntu
OEM install (for manufacturers)
Check disc for defects

==================== sdb: Location of files loaded by Grub =====================

           GiB - GB             File                                 Fragment(s)
            ?? = ??             boot/grub/grub.cfg                             1

======================== Unknown MBRs/Boot Sectors/etc =========================

Unknown MBR on /dev/sda

Unknown BootLoader on sdb

Suggested repair: ______________________________________________________________

The default repair of the Boot-Repair utility would not act on the boot.

Is there any way I can fix this without reinstalling the OS?
Any help is really appreciated.
  • 1
    You may want to install a newer version as Ubuntu 18.04 LTS is EOL at the end of May. It was supposed to end last day of this month but they gave it a 1 month extension.
    – David
    Apr 27, 2023 at 15:24
  • 1
    Maybe it's impossible to install something more recent. It could be a 32 bits machine. I'm not sure if this person has access to a full terminal (console), but, if yes, it is worth trying to type "startx" and "xinit" if "startx" fails. At least, if none functions, the error messages should give a clue.
    – Alain Reve
    Apr 27, 2023 at 17:01


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