If it is asking you to format, then it doesn't think there is anything on the card.
I'm assuming this is a used card that has had pictures on it. If that is the case, it sounds like you had an error on the card. You can try to reinsert it again and see if that makes a difference. If not, then you will need to format it. If there are pictures on it, you will have to run data recovery on the card and do a lost volume scan to recover pictures. Hope this helps.
-T