Not your fault, but your problem description is hard to follow. It sounds like you are saying that the fuel gauge needle has somehow shpronged itself around to the right side of the mechanical stop at the right side of its normal range. That wouldn't seem to be impossible although I can't recall that I've ever seen it happen in about 50 years of tinkering with electronics.
I doubt that the problem is the fuel level sensor in the tank, but it's (barely) possible that those clever Japanese have come up with a needle design that saves ten cents per car and behaves really oddly when the fuel level sensor gives an "impossible" reading.
Odds are that the gauge is broken and there isn't much you can do to fix it other than replacing the gauge. That probably means replacing the instrument cluster -- which won't be cheap. If the car is under warranty, take it to the dealer and let them worry about it. If not, talk to a good independent mechanic about the problem. Maybe when they see the problem, they will see an easy solution. If not they can probably replace the gauge/cluster -- maybe with one from a salvage yard.