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I was trying to install Ubuntu in a dual boot with win8, but I've installed several other distros in the past so I was quite confused by all the different partitions. I thought I'd solve this by booting into windows deleting all the Linux partitions and reinstalling, I assumed I'd be able to boot from USB just fine.

However, now when I start the laptop, a Toshiba Satellite, it just goes straight into grub rescue mode. It no longer shows the "press F12" to change the boot device order and pressing F12 has no effect.

In grub rescue mode "ls" command works and shows: (hd0) (hd0,msdos2) (hd0,msdos1) (hd1) (hd1,msdos1)

(I assume hd0 is my local hd and hd1 is my bootable ubuntu usb key)

However all other command seem to end in "error: unknown filesystem"

I've tried "ls (hd1,msdos1)/", this gives "error: unknown filesystem", as does "insmod normal".

I think my USB key uses a FAT32 file system, maybe this is why all other grub commands give "error: unknown filesystem"? If so how can I prepare a bootable USB stick with a linux partition?

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did you try the solutions here? – Nil May 4 '13 at 12:53
Yes, most of them won't work because I can't from USB. – Robert May 4 '13 at 16:33

I need a bit of clarification: Did you erase the partitions (as in format), or did you remove the primary partition (ext4, swap ect)? If you are able to boot from CD, I recommend download RescaTux ( and burning it to a disk to attempt a full repair.

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