Q: On the driver side of my car the low beam headlight doesn't work. I checked all fuses and changed the bulb, but it still doesn't work

Hey there. When you say you checked the fuses & the relays, and everything was getting power, did you check the actual outlet for power? You can use a voltmeter to test the available voltage at the bulb socket. You can also use an ohmmeter to test the resistance of the socket and make sure the socket itself has not failed. If this is the case, you will need to rewire a new bulb socket into place. If performing this at home, your main concern should be with making sure the new connections are protected from the environment. If you do not have the right amount of available voltage at the socket, you will want to trace from the fuses and relays to the socket every foot or so until you find where the voltage drop occurs. This is where your issue is and it must be corrected by whatever means necessary, which can only be determined once the issue was found. You may have a short or a damaged wire/connection along the way. If you would like to have this taken care of, a qualified professional, like one from YourMechanic, can come to your car’s location to diagnose the headlight problem and follow through with repairs.