I think, before I re-formatted I'd like to a) make sure the card is the problem and b) try to save any data on the card.
If you have access to a PC with a card reader (or you have a USB adaptor), see if the PC can read the card contents. If it can, copy all the data to the PC.
Alternatively, see if a friends phone can read the card. If the card is readable, see if you can persuade the friend to let you back up any key files on his phone.
Either way, if the card is readable, the problem may be with the phone. You'll need to try a different card (that you know works) in the phone to check this.
If the phone is OK and you've backed up anything critical from the card, then I'd think about formatting it.