I would be fairly confident that your files are still intact and that
it's just the case that the file system has somehow become corrupted.
Have you considered trying data recovery software? I seem to remember
that you said earlier in the thread that you have access to an XP
machine. Whilst it grieves me to suggest using a piece of windoze
software, it is the only one I have personal experience of - some of the
more experienced linux people on here might be able to suggest a linux
alternative. Download Recuva <http://www.recuva.com/> and install it on
the XP machine and see if it can find your files. This software is free
and proved very effective in recovering data when a virus killed the mbr
on my daughter's machine. If you can recover the files, it will free you
up to play around with reformatting the card.