To repair a car door latch, first unlatch or unscrew the trim panel inside the car door along with the window controls. Disconnect any electrical connectors behind the trim panel. Carefully remove the plastic water shield behind the panel without tearing it.
If the windows are manual, use a rag, and rub behind the window crank handle to release it from its anchor. For power windows, use a trim stick to pry off the window controls from the trim panel before disconnecting the electrical connection. Unlatch any rods connecting the locks and door handles to the door latch by hand. Undo the bolts that secure the latch to the door with a Torx wrench. Many car models place these bolts on the outside edge of the door frame.
Use one of the access holes to remove the latch from the door. If there are any wires attached to the latch, disconnect them carefully. Remove any packaging from the new latch, and insert it through the access hole. Reconnect any wiring, and bolt the latch into place with the Torx screws and wrench. Reattach the link rods to the handles and locks.
Carefully replace the water shield, and install the interior door panel. Engage the panel clips, and install the mounting screws. Replace the window controls or crank, and check the electrical connections in the door.