Check that the door hinges are intact and they are firmly secured with the correct number of screws.If you have a broken hinge and need to replace it you will need: a new hinge, some screwdrivers and Phillips (cross-head) and a flat-head screwdriver, a hammer, a thick nail and some WD40 or Teflon spray. Once a year lubricate the hinges with silicon spray, grease or oil. This is best done when you remove the pin from the hinge. To do this you only need to remove one pin at a time. You may need to replace/adjust the hinge bearings occasionally.
Locks and deadbolts will also require oiling. You can use WD40 to oil the lock and use the directional nozzle to oil tricky areas. When you do this use the key in the lock to help spread the oil inside. Do not paint over locks. This will cause problems inside the lock.
Also see: Keys.