What's wrong with my camera? - 1

My camera is Nikon and one day I was snapping away at stuff and went to turn it off, it turned off fine but the lens still stayed out and now I can't turn it back on. The small green light still goes on when I press the start button, but then goes off after about five seconds. Can you please help me to figure out what's wrong?

Maybe you bumped the lens or got some dirt in it. It must retract. Here are some of my favorite repair sites.
http://camerarepair.blogspot.com/
http://www.fixya.com

http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html
http://www.fixya.com/tags/got_sand_in_camera
http://camerarepair.blogspot.com/2007/11/fixing-or-replacing-broken-lcd-screen.html
http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html
http://www.fixya.com/tags/spilled_soda_camera

Since you didn't mention the model I'll assume it's a small pocket toy. Also, since you didn't mention its age, I'll assume it's over one year.

If both are true the camera is probably done. These small, cheap cameras are designed to last just past the warranty period of one year. Then they become like and old cell phone, a throw away item.

If that's the case you have one choice, trash and replace.