I know the pain- when I was in college, I was working in my composion class. I had 4 movements of a six part symphony lost in the void of digital space. the back up I made was unreadable for some reason - old Zip drive disc. I was lucky that I had dropped it to a cassette and had the hard copy of the score, or I would have failed that class. I have never re-entered it.

on another note, I have used cdcheck to find errors on discs it has worked when other things have not - it's free, so no harm to try.

good luck on the recovery.