Electrical Outlet Not Flush with the Wall?

My basement was refinished just before we bought the house. I'm pretty sure the previous owner did the work himself as there are so many problems. Several outlets seem to have the faceplate screwed just into the drywall, and are always falling off. Now one of the outlets has no faceplate and is popping way out of the wall. I don't know how to begin to fix this, but I'm pretty sure there must be a relatively easy way to do it?

By Amy Fletcher C. from Louisville, KY