After you identify and stop the leak, the affected part of the drywall may have to be removed. A small area can be restored by scraping away the damage using a putty knife. Sodden drywall will simply crumble to the touch and can be cleared away. You may also have to peel off wet drywall tape and replace it. The now-exposed area should then be dried out for 48 hours, according to True Value, using a dehumidifier or fan.
Next, patch it with a separate piece of drywall. Constellation recommends using a gypsum-based joint paste (aka drywall mud) to cover and fortify any repairs. Fiberglass tape can be used in tandem with the mud to prevent future cracking. Smooth the paste, and once dry, the fixed section is ready to be sanded, coated with a stain sealant, and painted.
If the water damage to one’s ceiling is not extensive, such repairs are fairly minimal and don’t require a plethora of equipment. However, as you are likely to be working overhead, and possibly manipulating heavy pieces of drywall, having an assistant is a bonus.