My computer has (had) a dual boot of Ubuntu Precise and Windows 7. Recently, when I started the computer, grub gave me an error saying "Unknown filesystem", and sent me to grub rescue. I searched for solutions to this, and found this answer: Unknown filesystem error: grub rescue. I followed the instructions there, but they didn't really help: when I restarted the computer, it went straight to Windows without grub intervening at all (so it boots successfully, just not to the OS I want). This is the log from boot-repair. My Ubuntu partition is sda6.

Naturally, I'm a little worried, since the log says "unknown filesystem type ''", which to me looks like the partition might be corrupt somehow. From the Ubuntu Live CD, I started gparted and looked at my partitions, and it also told me that my sda6 is an unknown filesystem.

So my questions are basically:

1. Can I restore Ubuntu to the way it was?

2. If not, can I at least rescue the data I had on the partition somehow?

3. Again, if I can't restore Ubuntu, how do I clean everything up so that I can reinstall it without too many complications?

Another thing I should mention is that yesterday I had a similar problem where the computer told me there was a problem with the hard drive when it was starting, but it fixed itself by running fsck (that time it got past grub, and managed to start Ubuntu). Between that occasion and me having trouble booting the computer today, I have booted it successfully at least twice.

Thanks for any help!