if you just stripped the thread, it should screw out. if you stripped the head there are a couple things you can do: first heat up your screw driver bit with a torch, until it is almost red hot, then push the bit into the head of the screw for about a minuet, letting the heat transfer into the screw, then firmly unscrew. this only works if the head is slightly thrashed and is not necessarily good for your screwdriver. the other option is to drill the screw out. use a 2mm bit to drill down the screw shaft about a millimeter, then follow with a 5mm bit. this will result in the screw head popping off. finally use a hacksaw to cut the top of the screw flat with the topsheet. these are the only ways i know how to remedy this problem, but id like to hear other options