Hi all. For many months, my mother used her Samsung 870 EVO SSD with Ubuntu Mate 24.04.1 LTS (only) installed on it. It worked fine, until one day it stopped booting up, the black screen displaying the message “No Operating System detected”.
I’m sure that her hardware is still good enough to run Ubuntu Mate, as I’m able to use a secondary NVME SSD (just connected to a USB2 port) on it, with no problem at all. The problem Samsung internally-mounted SSD above is probably less than 2 years old and has hardly been used. Using my NVME SSD, I got the assessment "Disc OK" for the problem Samsung but reports 5 bad sectors. Are these perhaps a problem on an SSD? Preventing it from booting up? I did a png screenshot of it and I hope that my upload of it below here, can be opened:
Having encountered similar-looking “GRUB” problems from time to time in the past, I tried fixing the problem with an old boot repair disk USB key I had (perhaps unwisely, as it dated from 2014). It worked in the past, but this time it didn’t. In July 2024, I followed Ubuntu guides to get the latest version at the time. I believe that this boot repair key uses Linux Mint (LM logo is displayed); I updated it, as per its recommendation.
Using this latter boot repair key, the boot info report says that Ubuntu 24.04.1 LTS is indeed STILL present on sda5 (BTW Through my secondary NIMH SSD, I can see that all my mother’s files are still intact on the problem SSD)
I’m very wary about removing the “Grub2 files” and then having to try to install another bootloader (especially when I have no idea how to do this!). Here’s the PNG screenshot upload, hoping it can be opened:
I’d be very grateful for any advice you have how a NOVICE like me, can solve this problem (ideally with less effort involved than reinstalling UbuntuMate and all my Mum’s files)! Including if I’ve been perhaps barking up the wrong tree! 
I saved the boot info report as a text file, but the forum system will not allow me to upload it. So I’m pasting it below here:
boot-info-4ppa2081 [20250102_0110]
============================== Boot Info Summary ===============================
=> Syslinux MBR (4.04-4.07) is installed in the MBR of /dev/sda.
=> Grub2 (v2.00) is installed in the MBR of /dev/sdg and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and looks
for (,msdos1)/boot/grub. It also embeds following components:
modules
---------------------------------------------------------------------------
fshelp ext2 part_msdos biosdisk
---------------------------------------------------------------------------
sda1: __________________________________________________________________________
File system: vfat
Boot sector type: FAT32
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:
sda2: __________________________________________________________________________
File system: Extended Partition
Boot sector type: -
Boot sector info:
sda5: __________________________________________________________________________
File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Ubuntu 24.04.1 LTS
Boot files: /boot/grub/grub.cfg /etc/fstab /etc/default/grub
/boot/grub/i386-pc/core.img
sdg1: __________________________________________________________________________
File system: ntfs
Boot sector type: Windows 2000/XP: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:
sdb: ___________________________________________________________________________
File system: iso9660
Boot sector type: Unknown
Boot sector info:
Mounting failed: mount: /mnt/BootInfo/FD/sdb: /dev/sdb already mounted or mount point busy.
================================ 1 OS detected =================================
OS#1 (linux): Ubuntu 24.04.1 LTS on sda5
================================ Host/Hardware =================================
CPU architecture: 64-bit
Video: 82915G/GV/910GL Integrated Graphics Controller from Intel Corporation
Live-session OS is Linuxmint 64-bit (Linux Mint 21.2, victoria, x86_64)
===================================== UEFI =====================================
BIOS/UEFI firmware: A03 from Dell Inc.
This live-session is in Legacy/BIOS/CSM mode (not in EFI mode).
============================= Drive/Partition Info =============================
Disks info: ____________________________________________________________________
sda : notGPT, no-BIOSboot, has-noESP, not-usb, not-mmc, has-os, no-wind, 2048 sectors * 512 bytes
sdg : notGPT, no-BIOSboot, has-noESP, usb-disk, not-mmc, no-os, no-wind, 2048 sectors * 512 bytes
Partitions info (1/3): _________________________________________________________
sda1 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
sda5 : is-os, 64, apt-get, grub-pc , grub2, grub-install, grubenv-ng, update-grub, end-after-100GB
sdg1 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
Partitions info (2/3): _________________________________________________________
sda1 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, vfat
sda5 : isnotESP, fstab-without-efi, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ext4
sdg1 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ntfs
Partitions info (3/3): _________________________________________________________
sda1 : not–sepboot, no—boot, part-has-no-fstab, not-sep-usr, no—usr, part-has-no-fstab, no–grub.d, sda
sda5 : not–sepboot, with-boot, fstab-without-boot, not-sep-usr, with–usr, fstab-without-usr, std-grub.d, sda
sdg1 : not–sepboot, no—boot, part-has-no-fstab, not-sep-usr, no—usr, part-has-no-fstab, no–grub.d, sdg
fdisk -l (filtered): ___________________________________________________________
Disk sda: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk identifier: 0x422df5ef
Boot Start End Sectors Size Id Type
sda1 2048 1050623 1048576 512M b W95 FAT32
sda2 1052670 976771071 975718402 465.3G 5 Extended
sda5 * 1052672 976771071 975718400 465.3G 83 Linux
Disk sdb: 7.5 GiB, 8053063680 bytes, 15728640 sectors
Disk identifier: 0x14eb2669
Boot Start End Sectors Size Id Type
sdb1 * 0 5138431 5138432 2.5G 0 Empty
sdb2 572 9067 8496 4.1M ef EFI (FAT-12/16/32)
sdb3 5140480 15728639 10588160 5G 83 Linux
Disk sdg: 114.61 GiB, 123060879360 bytes, 240353280 sectors
Disk identifier: 0x162ec9ef
Boot Start End Sectors Size Id Type
sdg1 * 2048 240351231 240349184 114.6G 83 Linux
parted -lm (filtered): _________________________________________________________
sda:500GB:scsi:512:512:msdos:ATA Samsung SSD 870:;
1:1049kB:538MB:537MB:fat32::;
2:539MB:500GB:500GB:::;
5:539MB:500GB:500GB:ext4::boot;
sdb:8053MB:scsi:512:512:msdos:General UDisk:;
2:293kB:4643kB:4350kB:::esp;
3:2632MB:8053MB:5421MB:ext4::;
sdg:123GB:scsi:512:512:msdos:SanDisk Ultra USB 3.0:;
1:1049kB:123GB:123GB:ntfs::boot;
Free space >10MiB: ______________________________________________________________
sdb: 4.43MiB:2510MiB:2506MiB
blkid (filtered): ______________________________________________________________
NAME FSTYPE UUID PARTUUID LABEL PARTLABEL
sda
├─sda1 vfat 3B26-7C17 422df5ef-01
├─sda2 422df5ef-02
└─sda5 ext4 b0750895-bf20-4e21-897d-cc0e64bb3a25 422df5ef-05
sdb iso9660 2023-12-23-05-05-55-00 Boot-Repair-Disk 64bit
├─sdb1 iso9660 2023-12-23-05-05-55-00 14eb2669-01 Boot-Repair-Disk 64bit
├─sdb2 vfat 8D6C-A9F8 14eb2669-02 ESP
└─sdb3 ext4 2af65e8e-754c-4ecf-8d77-6875dd72c70e 14eb2669-03 writable
sdc
sdd
sde
sdf
sdg
└─sdg1 ntfs CE2840C32840AC71 162ec9ef-01 usb
Mount points (filtered): _______________________________________________________
Avail Use% Mounted on
/dev/sda1 511M 0% /mnt/boot-sav/sda1
/dev/sda5 380.7G 12% /mnt/boot-sav/sda5
/dev/sdb1 0 100% /cdrom
/dev/sdg1 113.8G 1% /media/mint/usb
Mount options (filtered): ______________________________________________________
/dev/sda1 vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
/dev/sda5 ext4 rw,relatime
/dev/sdb1 iso9660 ro,noatime,nojoliet,check=s,map=n,blocksize=2048,iocharset=utf8
/dev/sdg1 fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096
====================== sda5/boot/grub/grub.cfg (filtered) ======================
Ubuntu b0750895-bf20-4e21-897d-cc0e64bb3a25
END /etc/grub.d/30_os-prober
UEFI Firmware Settings uefi-firmware
END /etc/grub.d/30_uefi-firmware
========================== sda5/etc/fstab (filtered) ===========================
/ was on /dev/sda5 during installation
UUID=b0750895-bf20-4e21-897d-cc0e64bb3a25 / ext4 errors=remount-ro 0 1
/boot/efi was on /dev/sda1 during installation
/swapfile none swap sw 0 0
======================= sda5/etc/default/grub (filtered) =======================
GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=( . /etc/os-release; echo ${NAME:-Ubuntu} ) 2>/dev/null || echo Ubuntu
GRUB_CMDLINE_LINUX_DEFAULT=“quiet splash”
GRUB_CMDLINE_LINUX=“”
==================== sda5: Location of files loaded by Grub ====================
GiB - GB File Fragment(s)
331.181144714 = 355.603046400 boot/grub/grub.cfg 1
460.661121368 = 494.631112704 boot/grub/i386-pc/core.img 1
28.751949310 = 30.872170496 boot/vmlinuz 2
330.859024048 = 355.257171968 boot/vmlinuz-6.5.0-44-generic 2
28.751949310 = 30.872170496 boot/vmlinuz-6.8.0-45-generic 2
330.859024048 = 355.257171968 boot/vmlinuz.old 2
31.626850128 = 33.959071744 boot/initrd.img 3
126.751960754 = 136.098881536 boot/initrd.img-6.5.0-44-generic 8
31.626850128 = 33.959071744 boot/initrd.img-6.8.0-45-generic 3
126.751960754 = 136.098881536 boot/initrd.img.old 8
===================== sda5: ls -l /etc/grub.d/ (filtered) ======================
-rwxr-xr-x 1 root root 18133 Apr 4 2024 10_linux
-rwxr-xr-x 1 root root 43202 Oct 2 2023 10_linux_zfs
-rwxr-xr-x 1 root root 14513 Apr 4 2024 20_linux_xen
-rwxr-xr-x 1 root root 786 Oct 2 2023 25_bli
-rwxr-xr-x 1 root root 13120 Oct 2 2023 30_os-prober
-rwxr-xr-x 1 root root 1174 Oct 2 2023 30_uefi-firmware
-rwxr-xr-x 1 root root 722 Feb 26 2023 35_fwupd
-rwxr-xr-x 1 root root 214 Jul 31 2020 40_custom
-rwxr-xr-x 1 root root 215 Apr 15 2022 41_custom
======================== Unknown MBRs/Boot Sectors/etc =========================
Unknown BootLoader on sdb
Suggested repair: ______________________________________________________________
The default repair of the Boot-Repair utility would purge (in order to reset grubenv) and reinstall the grub2 of
sda5 into the MBR of sda.
Grub-efi would not be selected by default because no ESP detected.
Additional repair would be performed: unhide-bootmenu-10s
Final advice in case of suggested repair: ______________________________________
Please do not forget to make your BIOS boot on sda (ATA Samsung SSD 870) disk!
The boot files of [sda5 (end>100GB)] are far from the start of the disk. Your BIOS may not detect them. You may want to retry after creating a /boot partition (EXT4, >200MB, start of the disk). This can be performed via tools such as gParted. Then select this partition via the [Separate /boot partition:] option of [Boot-Repair]. (BootPartition - Community Help Wiki)
Many thanks in advance for any help! 
