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I have had Ubuntu 12.04 x86 (32-bit) for a while now and decided to erase it and reinstall it just to clear some memory and start over.

I have performed this operation before and it worked fine, but after restarting this time, I got an ELF header smaller than expected error and a grub rescue prompt. I am not so concerned about the error this time because I know that the operating systems and all my files are still there (at least I think they are after running the ls command at the prompt - example drive: (hd1, msdos6)?).

I would boot from the Live CD and make changes inside, but the optical drive does not work, and my Dell Optiplex GX260 does not have the BIOS capability to boot from the USB drive I installed. I have done some research, and it sounds like GRUB is corrupted and/or did not install right. Maybe this had something to do with the fact that it was already installed, or where it was installed.

Do I have to set the path and root drive for GRUB, or what can I do to get the operating system up and working again?

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did you try to press the e key when you are under Grub? – user827992 Jul 6 '12 at 21:20

Using another PC, download "Boot-Repair-Disk," burn the ISO image to a CD and boot from it. It should work. (It did for me.)

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boss his optical drive is not working and bios wont allow flash boot. so what use of making bootable image – Amit Rane Aug 1 '12 at 8:04

You can type the command at grub rescue:

grub-install /dev/sda

Quit the grub rescue mode and reboot the machine.

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unknown command grub-install :-( – garakkio Oct 24 '13 at 7:28

If grub is installed but corrupt

sudo update-grub
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