Why does my door open when locked?
Either the door frame is too wide, or the insert in the door is installed too far inside away from the edge of the door so that it does not go all the way far enough into the strike plate cavity, so as to remain shut when force is applied to the door.
How do you keep a door from opening when locked?
Use a door wedge or door stopper. This works for doors that open inwardly. A door stopper is designed to keep the door open, but if it is placed behind the door, it serves as a barricade. Burglars will have a hard time opening the door.
How do you fix a lock that won’t turn?
If that is the problem, it is easy to fix. You can spray a little dry lubricant in the lock to free up the plug so you can open the door. Spray lubricant in the keyway and insert the key a few times so the lubricant can get worked into the mechanism. If a dry lubricant doesn’t do the trick, you can try WD-40.