Samsung 8GB MicroSDHC Not recognized

Hello,

I put this in Mobile: Android just because I can't see a better place to put it.

I've seen several questions similar to this one but haven't seen any answers that help me.
My phone (Sprint HTC) had an 8 GB MicroSDHC card in it. All of a sudden all of my settings went back to their defaults (ringtones, notification tones, etc) and all of my pictures were gone. Went to check the SD card and it said there wasn't one installed.
I pulled the card and didn't see anything physically wrong. I put it back in and it still wasn't recognized.

I had a spare 8 GB SD card around so I put it in the phone and restored from a backup (a few months old but still had most of my pictures and tones). I worked OK so the problem isn't the phone.

I put the defunct SD card in a reader and put in the slot in my PC (Windows Vista). Nothing. Not even a drive letter showing up in the 'My Computer' window. Tried in a Windows 7 laptop. Still nothing. The reader and slots word fine with other SDHC cards (8 and 32 GB). I'm beginning to think that the SD card is fried. I haven't tried any Linux tools yet because my Linux box doesn't have an SD card reader and I'd have to buy a USB one.

Thanks.