Ugh! The doorknob dented the wall, thanks kids. We have all experienced this at one time or another with children in the house. They opened the door too hard against the wall and bang, a dent.
A phone call to a contractor and $150 later it is fixed. What? No thank you I will handle this myself, and you can.
Two off the shelf items kept in your garage or closet can take care of this problem and many more in the future.
The second thing you need is a can of drywall spray texture. You can find this at most hardware stores. It has an adjustment dial to match your wall texture. All you have to do is shake, spray and maybe smooth it out with a trowel.
This is a easy as it sounds, and if you mess up you can wipe off, sand and redo the area as many times as you want till you are satisfied. Good luck!