I read this online and my camera does have a "reformat" button.
"I have the tl220 by samsung and the camera said that it couldn't read the micro SD card, even when the card was inside of the camera. I tried a bunch of things but could not get the camera to read it until i formatted my camera (its in the options) and it works fine. Thanks for the tip!"
Also read that sometimes the camera will lock and if you've set a password you will need to enter that and unlock it.
Tina, seems odd that if your computer once accepted your camera that it would just stop.