2002 Mercedes Benz C230

Electrical problem
2002 Mercedes Benz C230 4 cyl Wheel Drive Type unknown Automatic 48000 miles

Yesterday 1/16/2008, I put gas in my car and when I got home the gas hand showed empty. It was working fine the day before, I had a half tank of gas.
I put in more gas still there was no change, its not working. What would cause the gas hand not to work?
Also, the same day the dash board and radio lights are very, very dim. That has never happened before. The lights are always very bright inside my car.
What would cause the inside lights to look as if they are about to go out?

Thanks,
bb