ever tried the Panasonic formatter utility? it has done wonders for me, screwed up card that would show only a small percentage of its capacity, or nothing at all. there are about 2 variables to play with and in a couple of tries everything works again. I had a Nokia Micro Sd that i wanted to put in a camera, but the camera wouldn't read it, not even formatting it. So after much Googleing around i found that little app.
Just my 2 cents if it works for anyone.
http://www.sdcard.org/about/downloads/