my x box got knocked slightly the game that was in there at the time no longer works there is now a circle like scratch on the disk is there a way of getting this disk to work again
I believe this is what is known as a laser burn. The surface of the disk is damaged rendering it unreadable.
You can try taking the disk to a professional disk repair outlet (prices vary for this) The repair process uses a special system which actually removes a layer from the surface of the disk.
I have tried this myself before and found that the disk still would not work in my xbox but yet it appeared fine in a friends machine!