I agree with Drewed.
Firstly, do not format the card if you want to try and recover the photos. next...
If you haven't already tried. Take the batteries out of the camera, put them back in, turn on camera. If that works, great! if not...
Take card out and batteries out. Everything back in and turn on. If that works, great! if not...
Take card out and put into another card reader or camera (same brand would be good) and see what that says. If that doesn't work, find someone you know who may have data recovery software and see if they can have a look at the card and if any data is recoverable.
Adam