you may have stripped the hole(female). In that case you will have to drill it out a little and use a larger one-not the same size one. Keep your fingers crossed. If the screw is what is stripped you will have a hard time drilling it out because it will want to turn with the drill bit. Try to wedge(gently) something fine into the edge of the hole when you try to unscrew it or put pressure under the head of the screw as you try to remove it. Again, keep your fingers crossed. Pat