The lock cylinder in your Ford Ranger makes up a large part of the vehicle's ignition system. If your lock cylinder stops working correctly you will need to remove the lock cylinder from the steering column and replace it. You can pick up a replacement lock cylinder from your local auto store.
Open up the bonnet of your Ford Ranger and locate the battery. Use a wrench to remove the clamp bolt from the negative terminal. Lift the negative cable away from the terminal.
Remove the steering wheel cover from the steering wheel. Unclip the plastic connectors from around the edges of the steering wheel. If you cannot remove them with your hands, use a small flathead screwdriver to pry it off.
Locate the electrical wiring for the horn and the air bag if you have one. Follow the wiring until you locate the electrical connectors. Unhook the connectors from the steering wheel.
Use a Phillips-head screwdriver to remove the mounting screws on the steering column sleeve. Slide the sleeve off the column. Locate the ignition switch and remove the mounting bolts with a wrench. Place your key in the ignition and turn it to the locked position. This will give you access to the retaining pin. Unhook the retaining pin. This will allow you to remove both the ignition switch and lock cylinder. Unclip the lock cylinder from the ignition switch.
Attach a new lock cylinder to the ignition switch. Re-attach the steering wheel assembly by following the removal steps in reverse. Place a negative cable back on the terminal. Turn on the engine to check that the new lock cylinder works correctly.