How can I fill a screw hole so it can be used again?
If you are lacking a wooden peg or the skills to make one use round wooden toothpicks. Coat the toothpicks with woodglue. Place as many toothpicks in the hole as will fit. Gently tap in one more with a hammer. Break off any bits of toothpick that protrude from the hole. After the glue has dried, reinstall the screw.