Nikon D80 not taking pictures?

I haven't used my camera in a few months. I turned it on this evening and it won't take pictures. Somehow I got it to take a few, only with the flash on, and now it won't do anything.
Is there a setting I should change, or a way I can reset everything?
When I press the snap button, it turns the preflash light on and makes a sound similar to a film camera rewinding.

What do I do!

Try charging the battery.