I've missed the section in your comment that the files are missing in your cam now, too. Sorry.
If you're trying to read a card on any computer you should always (!) write protect the card before inserting it. All operation systems tend to write some system specific data to the card and sometimes this goes wrong. Might be the case here or the card is actually broken. Hard to tell from the distance. You could try a recovery tool to recover the photos (write protect the card).