[Fourdiesel]

Since all lights in that headlamp assembly are out the first suspect would be the connector the headlamp assembly slides into. Slide the headlight out and use a flashlight to make sure the connector the headlamp slides into is properly located. (check the other side if you wonder what it should look like.) Also take a look at the wires at the connector to see if any are broken or appear to be loose. You MAY be able to wiggle the connector around to the point where it makes a good connection.
If the plastic that holds the connector in place is broken or cracked it is a HUGE PITA to replace!