What happened to my pictures?

[KT Runner]

I got a new camera. I took some pictures and then put them on my computer using the memory card. All I did was copy the pictures and put them into a different folder and upload them to Facebook. I didn't delete them from the original folder on the memory card. When I put the memory card back into my camera, it wouldn't show my pictures. Is that what always happens when you put the pictures on your computer? Is there a way I can keep them on the memory card after putting them on the computer?