Fuel gauge problems

Well if you car has gas in it and it starts up and runs fine, my guess would be that the bobber that is attached to the fuel pump is flipped upside down.

What I would do first is take it to a mechanic and get the correct answer, but if I am correct then the fuel tank will need to be dropped and the bobber will have to be readjusted back to the normal position in order to make sure it will read correctly.

Another possibility could be a loose wire on the dash or a bad wire connecting to the fuel gauge.

Hope this helps!