Based on limited information, I'd say that you likely have a dead card. What did you do? Hard to say. I have not had one die yet, but a digital recorder has (similar memory type). It happens, and they do have a finite life.
Typical-consumer-technical-ability-level (read non-nerd friendly) utilities for formatting (either device, OS, or third-party) typically give up and throw an error at the slightest problems, without further recourse to more involved utilities or data recovery options.
Best bet would probably be to try some of the analysis and/or data recovery utilities tools available on a thumb-drive multi-boot utility package. One such option is below.
http://www.pendrivelinux.com/yumi-multiboot-usb-creator/If the data is not valuable and/or you don't have the proficiency/adventurous spirit, you should probably consider it a loss.
I know. Horse/barn door. Storage is so cheap these days, that you should have a backup of all but the latest pics.
