How repair a large hole in sheetrock between window and corner.

If you run a utility knife down the corner and top will cut the tape. It would be easier to remove the sheet and replace to get a nice finish. Once you remove the sheet you will see that the rock is screwed to the studs and there will be one in the corner since the present sheet had to be tied in to a stud. Cut the face of the sheet rock using your knife and an "L" square. Cut the piece to size, install, tape corners and seams, mud evenly, sand, prime and then paint. With any luck you may be able to back the screws out of the rock to remove.

A patch will look like a patch if not done right. A large hole as your would be easier to replace with a whole sheet. Follow Joychevi instructions and your good.

As long as you have the wall open, check what's going on inside there. Insulation okay? Any gaps that should be filled? Do you see evidence of insects or pests? You can take care of that, now, too. Also, remember to prime your new piece of drywall with a good primer - preferably one that resists mold, like Kilz.

I watched the repair of a smaller hole on The This Old House on TV yesterday and they showed the repair for a smaller hole. They also have a web site you can tap into for expertise help. Another option is to cut the hole with straight edges making sure that you cut back from the edge of the stud so that you have enough stud to screw to. Once you have done this, cut a piece the size of the hole. With a hole that size there is probably another stud in the middle so this will give you something to screw to make it solid. Screw the piece in the corners and in the middle if possible. If there is no stud in the middle you may be able to put a board into the space and screw it to the studs on the side. Make sure the added board is even with the outside of the side studs. There is a sticky drywall tape available which you put on all seams. Then mud with the proper compound. Smooth over with your trowel so there is not too much to sand after. Let dry and then sand smooth. Prime and then paint. Be careful not to be too rough with the sandpaper as you could make the paper which covers the drywall rough and it will show when you paint.

This may be an easier solution for you. Good Luck!