If all else fails and you just want to recover files, you can also try testdisk and photorec (both are on Knoppix). photorec in particular is good for recovering files. It ignores the underlying file system and scans disks for byte patterns which match the signature of common file formats. So it might still work even if the filesystem is damaged and the disk cannot be mounted.

Photorec is good for media files like digital images (what it was originally designed to rescue) but now can recover many different types of files. Try a google for photorec to look at the main home site. It might be useful to you. Unfortunately, the documentation and manual is quite brief.