2000 Chevy Impala Front headlights

We were told by the dealer when in for repairs that in order to fix our driverside headlamp that we would have to purchase the whole unit. We found out how to remove the headlamp so that we could possibly change the bulb out. So we did. But the headlamp still wont work. We did have water inside and drained it out. Could that have damaged the wiring to the unit? Is there a fuse or something else we need to look at? Or new wiring to the headlamps. Cant find much in auto manuals.