You can repair a large hole in a wall by fitting in a patch cut from a scrap piece of wallboard. The patch will be held in place, or backed up by a backup plate. Follow the steps and illustrations below.
Use a keyhole saw or a sharp utility knife to make the hole's irregular shape an even square. This will allow the backup plate to fit behind it.
Use a piece of plywood or wallboard as the backup plate. Make it about 2 inches larger than the hole. Drill a hole in the center big enough for your finger.
Pass the backup plate into the hole and hold it in place while you screw into it through the wall with drywall screws while holding it in place with your finger. Or you can apply a glue around the edge to glue it in place instead of using the drywall screws.
