If I understand it correct, you are trying to format the memory card.
Before you format, I suggest you back up all your data. If your memory card has gone bad, you can try to recover data with this free program Recuva available at http://www.piriform.com/recuva . To format, you need to insert your memory card in card reader, go to My Computer, right click on drive letter (for example E: ) and you should see an option to format.