My 99 chevy silverado power window stoped working

This would more than likely NOT be a sensor problem.

In replacing the hinges you more than likely disrupted the wires that run from the cab into the door, causing a ground, pinching a wire or in some way causing no power to get through one of the wires. There is a rubber boot that runs between the door and the cab, pull it back and have someone hold the button in the down position. Then wiggle the wires until the window moves. That truck will have defog mirrors on it more than likeley so there will be plenty of wires to wiggle. When you find the problem wire simply cut the problem area, replace it with an end to end connector (**** connector) and seal it with silicone. If it is not one of the wires, you more than likely had a wire come off inside the door. (depends on how much you horsed it when you were changing those hinges) Thats where i'd start.

Best Of Luck!