Hi and welcome!
this sounds like a real problem. If you cannot access the card, then there's little you can do about it. Have you tried another card reader? That might be able to help. The first thing is to access the card, then you'll see if a photo recovery software can get your pictures back, after which you should format the card (if you can, do a Low Level format). But I wouldn't trust that card for important data if it failed once.
There has been multiple reports of xD cards failing, much more so than any other types of cards. There is a thread here about just that problem, you might want to read it:
http://www.digicamhelp.com/cgi-bin/yabb/YaBB.cgi?board=access;action=display;num=1113273374