In most states you are required to have your number plate illuminated after dark. If the light above the plate burns out, you risk being pulled over and ticketed by the police. You could take your car to a repair shop to have the problem fixed, but it would be a waste of money. Replacing a number plate bulb in a 2002 Ford Focus is an easy task, requiring only minutes to accomplish.
Turn the headlamp control to the "Off" position to avoid the risk of an electrical shock.
Locate the number plate lights. They are mounted in the boot in the recessed area above the rear number plate.
Use a flathead screwdriver to gently pry the light assembly out of its housing.
Pull the bulb straight out if its socket. It should come out easily. If it does not, twist it slightly and try again.
Plug a new bulb into the socket.
Press the light assembly back into its housing. It will snap in place.