Scrape off damaged bits of the ceiling with a putty knife. Hold a piece of cardboard under the ceiling while scraping to catch the falling debris. Be sure to wear goggles and a mask to prevent inhalation.
Pin down a plastic tarp one foot around all four sides of the damaged area with push pins. Let the tarp drape down four feet. This will create a barrier to prevent the paint spilling onto unwanted areas.
Lay drop cloths on the floor beneath the damaged section.
Spray stain-blocking primer on the damaged surface. Let it dry.
Shake a can of acoustic texture and spray onto the damaged section. Follow the manufacturer's directions to yield best results. Hold the can 9 to 14 inches away from the ceiling. Let it dry.