Inspect all of the hinge screws. If any are loose, tighten them with a screwdriver or drill. If loose screws will not tighten, the hole is stripped. In this case, back out the screw, hammer a wood dowel pin into the hole and replace the screw. If there are no loose screws or if the door is still crooked after tightening the screws, move on to the next step.
Take measurements at the lower portion of the door if the bottom is rubbing. Measure the distance from the bottom of the door to the ground at the hinged side of the door, and at the outer end of the door. Subtract the first measurement from the second measurement to determine the amount of correction needed.
If the top of the door is rubbing, measure the distance from the top of the door to the head jamb at the hinged side of the door, and at the outer end of the door. Subtract the first measurement from the second measurement to determine the amount of correction needed.
Remove the part of the top hinge that is connected to the door frame, if the bottom of the door is rubbing. Remove the part of the bottom hinge that is connected to the door frame, if the top of the door is rubbing. This will reveal the hole in which the hinge was set, which is known as the mortise.
Shave wood from the bottom of the mortise, using a chisel and hammer, to deepen the mortise. Use the measurement from Step 2 to determine how much to deepen the mortise. Place a mark up from the tip of the chisel at the determined measurement, using a marker, to ensure that you chisel out the appropriate amount of wood. Hit the chisel straight into the wood, stopping at the mark, then turn the chisel to a sharp angle to remove strips of wood.
Reattach the hinge. The deepened mortise will bring in the top or bottom, straightening the door.