If the door latch in your car door is broken, you will have big problems keeping the door closed as well as possibly opening it. You need to fix the latch as soon as possible. The exact method of repairing the latch can vary, depending on the type of car you have, so it's a good idea to talk with your mechanic. However, there are many similarities, as the latch should be mounted within the door along the outer edge and connected to the handles and locks.
Detach the inner trim panel from the car door--remove the window controls, pry off all exterior trim panels (like the ones near the door handles), remove all the mounting screws with a screwdriver, pry the panel off its clips with a trim stick and disconnect all electrical connectors behind the panel.
Peel away the plastic water shield behind the door trim panel, taking care not to tear it.
Disconnect the rods that connect the locks and the door handles to the latch; you should be able to detach them by hand.
Remove the bolts holding the latch to the door; they are usually on the outer edge of the door frame and usually require a Torx wrench. Pull the latch out of the door through one of the access holes and disconnect any wiring connected to it.
Insert the replacement latch into the door, connecting any wires that are needed, and bolt it in place with the Torx screws and your Torx wrench. Connect the link rods to the handles and locks.
Paste the water shield back in place over the door.
Install the inner door panel in place in the reverse order of removal, making sure the panel's clips engage, applying the mounting screws and attaching the trim panels and the window controls.
