How to fill a hole in drywall the size of a door nob.

wow! I hope you put some sort of spring mechanism or stopper to prevent that from happening again. Here is a link on how to patch the drywall

https://www.bing.com/videos/search?q=patching+a+hole+in+drywall&&view=detail&mid=EDF5BAE61F14B670B0D4EDF5BAE61F14B670B0D4&&FORM=VDRVRV

There is a "patch" sold at hardware stores (Lowe's, Home Depot, etc) for just such accidents. It fits over this type of hole and has a strong adhesive that allows the patch to fully cover this "oops". I believe the patch is made out of plastic or some other lightweight product but it does the job in a very finished fashion and quickly. It is only $4 or so.

Once repaired, install one of these:

We had this same problem when we moved into our home (it was a foreclosure). We bought a wall repair netting (it is yellow and sticky on the back side) to cover the hole. Then we applied a wall repair plaster over the whole netting area...making sure the netting is completely covered. Let it all dry for a couple days and then sanded it smooth and level with the rest of the wall. If you want to try and match the texture, there is a spray on texture spray available but we decided we didn't want to try and replicate the texture so we covered the bottom part of the wall with beadboard and thus totally hiding the wall patch. Love the way it turned out.

You need to be sure there's one of those small doors toppers installed either on the door or on the wall near the floor so this can't occur again. They screw in easily to either area.

Hi Bar! First off, cut the hole bigger. You want a nice neat square hole with even edges. Then slip a piece of shim into the hole and screw it to both sides through the sound drywall.

Next, cut a piece of new drywall the same size as the hole, insert and screw into the shim.

Using a 3 or 4 inch drywall knife, fill with drywall compound, not spackle, across the entire damaged area. Scrape with the knife to make sure it's level.

Let this dry thoroughly. Sand lightly, Then take a 12" drywall knife and skim coat the area with additional compound feathering out well into the undamaged area.

Once dry, sand this until your fingers can't tell any difference in elevation.

Prime with primer, then paint