Remove the screws from the doorknob using a screwdriver and remove the knob out of the door.
Remove the screws in the door hinges from the door jamb and door frame using a screwdriver or cordless drill.
Place the door in a door vise on your workplace floor with the hinged jamb up.
Set a square on the jamb level with the edges of the existing hinge. Trace the square to mark the top and bottom of the hinge onto the other side of the jamb. Repeat this for the bottom hinge.
Use a tape measure to measure the width of the hinge and mark this width for the new hinges on the opposite side of the jamb.
Cut out the new hinge area with a chisel and hammer, cutting small 1/4-inch sections at a time until the entire hinge area is clear.
Sand the recessed area to remove splinters and roughness.
Fill in the previous hinge recess on the door and in the door frame with wood putty. Allow to dry for 24 hours and sand the wood putty for smoothness.
Use a tape measure to determine the position for the hinges on the door frame. Measure the top of the upper hinge from the top of the door frame and the bottom of the lower hinge from the floor.
Mark the door frame on the opposite side according to your measurements.
Attach the hinges to the door frame using a cordless drill and the previously used screws at the new marks.
Attach the door to the hinges with the previously used screws and a cordless drill.
Insert the doorknob into the hole with the lock facing into the room.