If you have a child taking karate classes, they may think your bathroom is a good place to practice their kicks. If they did this and left a hole in the drywall, you have a repair on your hands. If the hole is small, you may be able to fix the drywall all on your own using a drywall patch.
Smooth Out the Area
Before you get started, remove any frayed edges around the hole using a utility knife. You want the area around the hole to be as flat and smooth as it can get.
Clean the Area
Clean the area around the hole so the patch will adhere to the wall. You can use plain water to wipe it down. You do not want to saturate the drywall, so make sure you wring the cloth out after you dip into the mixture. If the drywall is dirty and plain water does not clean it, you can use a mixture of soap and water. Just make sure you rinse the soap off when you finish.
When you are finished cleaning the area, let it completely dry before continuing. This may take about an hour or so. The drywall patch will not stick to the wall if it is wet so rub over the area with your hands to ensure it is dry before you continue.
Apply the Drywall Patch
The drywall patch should be about as large as a sheet of paper. Because you likely do not need this much, you can cut it using a pair of scissors so that it is a little larger than the hole.
Remove the backing from the patch and place it over the hole. Use a putty knife to smooth it down. This will also remove any air bubbles that may be in it. The patch will leave a small raised area. To fix this, purchase joint compound at a home supply store. Using a putty knife spread the compound over the area around the hole to smooth it out. Let the area completely dry, and then use a piece of drywall sandpaper to wipe over the area until it is completely smooth. The hole should now be fixed and ready to paint.
If the hole in your drywall is larger than a small hole, you should consider hiring a drywall contractor (such as Zip Drywall) to repair it for you. Fixing a larger hole is much more difficult, and this will ensure it is repaired properly.