Why won't my pictures from my SD card show up on my camera?

I have a 4 GB card for my Nikon D3000… For some reason the pictures show up on my computer but when i put it into my camera, none of the pictures showed up… It said something like "no pictures on folder" or "folder empty"… What's wrong and can i fix it?

They won't show up if the pictures were not taken by that particular camera. What difference does it make? The images do you no good in your camera.

If you loaded these images from your computer your camera can't see them… In fact it can't read any file, even those taken by it after they've been moved because they've been altered slightly during the move.

Besides all that these SD cards are given to failure when used this way so don't. The work flow:
shoot - upload - format the card in the camera.

Your camera is not a photo viewer, it will probably only "properly" ever show photo's it's taken. To save on program space and complexity, most cameras do not fully implement decoding of the various formats or even sizes of the picture types - they tend to only be able to display their own types at the sizes they take!