What he said^^^^ Double check hi and lo at the plug for 12vdc using a chassis ground and then with the plugs ground. I bet the ground at the plug is bad. Back-trace it and reground it.
i failed to mention i have ranger headlights.... and todd i have tried diffrent bulbs its wierd one side is working and if i take the bulb from drivers side and plug it in on the passenger side it works.....