If it's a screw that it you don't need to get out and it's just serving as a fastener, use a nail set and a hammer to gently tap it just below the surface and patch over the hole just like you would a nail.
If it's a screw you need to be able to get out like this hinge screw you'll need a screw retractor. You can pick these up at any hardware store for a couple bucks.
First you need to drill a small pilot hole so the retractor has something to hold on to. match your drill bit and retrator to the size of the screw that you're trying to remove.
Once you've got the pilot hole usea hammer to gently tap the retractor in place.
Then, using a wrench push down on the screw while turning the retractor counter clockwise, you'll see the screw start to twist out.
Continue twisting until the screw is completly removed! Now all you have to do is replace it with a new screw. I'm Mrs. Fixit and it's just that simple!