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I believe Grub has accidentally become corrupted on my computer/laptop - when I turn it on, and try to boot into Ubuntu, Grub gives me the error message:

error: unknown file system

grub rescue>

Does anyone know how to fix this problem?

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that doesn't mean that your whole hard drive is corrupt, just the boot loader (grub) having some problem. There are various ways to fix that, hopefully leaving you with a working system without any lost data. – ImaginaryRobots Apr 26 '12 at 18:16

Yep it seems that your grub has been corrupted.

First of all burn a live CD or USB and boot into it.

Once in, connect to the internet and download Boot Repair (Link at the bottom or enter commands below)

The commands you need from the website are as follows :

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

sudo apt-get install -y boot-repair && boot-repair

Enter these into the terminal and it will install Boot Repair.

This tool will help you reinstall grub, it is fairly simple to use but if you need help either consult the documentation (same link) or comment below and I'll see if I can help you out some more!

Hope this helps,


Boot Repair Link

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ross thanks very much im just having a little trouble when i boot up the boot repair cd it says no DEFAULT or UI configuration or directive found! then it says boot: and im supposed to type something i tried C: then it said could not find kernel image: C:. Do you know what i am supposed to do? thx – Jesse Apr 26 '12 at 18:20
If you are booting with a Boot repair CD I would suggest using a standard Ubuntu live CD and installing Boot repair onto it once connected to the Internet; I find this method easier to do and less problematic. Let me know if this doesn't help. – Ross Fleming Apr 26 '12 at 18:26

the easiest way is that you get a boot-repair disk and burn it to a cd and fix the boot.... check this link

ok another way is to use your ubuntu live cd and use it to fix the boot check this website the portion starts with recover grub.. it uses live cd alone and uses manual partitioning installation (without formating the drive ) to recover grub...

also give a go to this community website, which describes the procedures for using the boot-repair software with in ubuntu live cd (Internet connection required)

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