Nikon camera won't detect SD memory card

I was oindering if any-one can help. I have had my nikon camera for about 12 months and my SD memory card for about the same time. In all of that time I have never had a problem with the camera using the card and have used about a quarter of the card with images from the camera.

All of a sudden the camera will not detect the SD memory card.

I have tried using the card on my PC and this works fine, and I can see all of the images. There is also plenty of free disk space.

I'm not sure what to do.

Has any-one else had this problem and if so how did you resolve.

Please help.