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i'm a fresh ubuntu user and I've installed a double boot with Wind 8 and Ubuntu 13.04, but since yesterday I'm receiving an error showing:

error: unknown filesystem grub rescue>

The fact is when I do ls (hdX,gptY)/ all I get is "error:unknown filesystem" again.

And the solutions posted don't work because I don't know why but I can't access the BIOS pressin F2 or to the boot pressing F12, the simply don't work since the error.

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What solutions had been posted? Does the screen with the brand of your PC appear? If no, try pressing F12/F2 while switching on. – the_Seppi Oct 1 '13 at 7:17
I tried making a live USB but as I don't have access to the BIOS I'm not able to boot it. The brand apppears but it doesn't matter when I press F2/F12, nothing happens. It used to work but not now. – lhynre Oct 1 '13 at 7:40

Get a live USB memory stick/CD etc. with Ubuntu and chroot into your system (more on that here: Then in the terminal which is chrooted into your system, type update-grub. Then close the terminal and re-boot to your hopefully-working GRUB!

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Hi, the problem is that I don't know how to enter the BIOS setup and thus I can't boot a USB/CD – lhynre Oct 1 '13 at 9:09
What does your computer show for literally one or two seconds before anything else? Is there the manufacturer's logo? That's the time to press a function key. Also does your keyboard have a function lock (like num lock)? – user171354 Oct 1 '13 at 10:24

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