There are five common reasons why your car door lock is not working.
The key fob battery is dead: This is one of the most common reasons why your car door lock is not working. If your locks aren't working, replacing the battery in the key fob could solve the issue.
The key fob is faulty: If the battery isn't the problem, the issue may be with the fob itself. If you go to your car dealer, they can hook the fob up to a computer and make sure that the programming is still good. If it's not sending a signal, the fob will likely have to be replaced.
A fuse is blown: If one door doesn't work, but others do, the problem could be a blown fuse. Replacing the fuse will correct the problem. This is a cheap and easy fix.
The solenoid is bad: Again, if one door doesn't work, but others do, the problem could be with the door lock solenoid. Replacing it may require removing the car door panel.
You have a broken wire: If the lock isn't getting power, hold the lock switch either up or down, and then open and close the door repeatedly to see if the lock will work. If it works sometimes, you probably have a broken wire.