Examine the hinges and see if they are sagging downward. Look for the outline of the hinge against the doorjamb. If you see the outline of where the hinge used to be located, then the hinge has moved over time.
Tighten all of the door hinges, using a screwdriver. This should help situate the door back in its proper position. Close the door to see if the door latch catches and the door shuts properly.
Place a level on top of the door. If the door is still uneven, you may have to raise the door slightly and retighten the hinges.
Place a rolled-up magazine or newspaper under the bottom of the door. Loosen all of the door hinges enough so you can tilt the door until it is level. The magazine will help keep the door from falling to the floor once you loosen the hinge screws.
Have an assistant hold the door level. Examine the level while your assistant is holding the door. Once the door is level, tighten down all of the hinge screws. The door should now be even and should latch and shut properly.
Replace the hinges if they are bent and you cannot screw them back into their proper position.