A sticking door latch makes it difficult to easily open and close a door without causing damage. A stuck latch may be a symptom of misalignment or something as basic as a need for lubricant. The source of a latch problem usually can be diagnosed simply by watching the function of the latch as the knob is turned and when the door closes. Fix a door latch that is stuck by identifying the problem that is making it stick and eliminating the issue.
Twist the door knob with the door open to see if the latch is sticking or returns to the fully extended position. Unscrew the two screws holding the door knobs and two holding the latch in place and slide all the hardware out of the door. Apply a small amount of silicone spray through the long straw nozzle extension into the in two holes on the top of the latch.
Slide the lubricated latch back into the door and replace the screws that held it and the door knobs in place. Move the lubricant within the latch mechanism by turning the door knobs back and forth several times until you feel the latch loosen and reset to full extension quickly. Wipe the section of the door below the latch if any of the lubricant comes out during operation of the door knob.
Watch the latch as the door closes to see if it is properly aligned with the strike plate. The strike plate is the metal piece screwed into the door frame where the latch holds when it is fully extended into the frame. Unscrew the two screws holding the strike plate to remove and reattach the plate so the latch goes right into the centre when the door closes.
Check the condition of the door hinges if you are having difficulty lining up the strike plate. Tighten the screws that hold all the hinges to the door and frame and tap the hinge pins with a hammer until they are flush to the hinge.
Test the latch to see if it still is sticking by closing and opening the adjusted door several times. Consult a locksmith or replace the latch mechanism if it continues to stick.
Pay attention when you take apart the door hardware so that the knobs and latch are put back on in the same position they were removed.