Car won't start. It just clicks and wont turn over.

I just bought the car a week ago.. it's been running just fine then all of a sudden, I park for 3 minutes and then the car wont start anymore. It just makes a click and a pathetic little electronic-like whine/buzz. The battery is fine, I just had it checked at the mechanics 4 days ago, but tried to have it jumped anyway and nothing changed. Lights, stereo, etc.. all turn on but the engine wont turn over. I have plenty of gas, just had an oil changed, topped off all the fluids. The headlights don't dim or change at all when trying to crank. Any ideas?