I have a 2009 Scion XB. Yesterday I noticed my drivers side headlight was out. I replaced the bulb. However, that did not fix the problem. I checked the fuses, and tested the relay (in the fuse box under the hood). High beams work. It's just the low beam on the driver's side that is out.
Is there another relay anywhere else?
Any other ideas?

 

The 2009 wiring diagram shows four fuses, one pair (high beam 10A/low beam 15A) for each headlight. One relay for high beams wired after the one relay for low beams. so if your high beams work, then it's not a relay problem.

I would also double check the headlamp connector pins are OK, and otherwise the wiring harness might be damaged somewhere so follow along it looking for breaks.