I just successfully completed replacing both headlights on my girlfriends 2000 Toyota Camry. Here are the steps that I took.
Determine which headlight(s) is not working.
Purchase a replacement bulb(s).
Turn off the car and headlights.
Open the hood.
Look inside the hood directly behind the headlight that does not work.
Grab the bulb and casing (an L shaped tube) and as you are facing it rotate it clockwise about 1/8-1/4 turn until the notches on the bulb align with the grooves in the headlight fixture's opening.
Pull the bulb out out the headlight fixture.
Depress the plastic tab on the plastic connector and remove the bulb from the wiring.
Insert the replacement bulb into the plastic connector and press into place until the tab snaps into place and the bulb is firmly connected to the wiring.
Insert the new bulb into the round opening of headlight fixture by aligning the notches with the grooves on the fixture.
Rotate the bulb counter-clockwise until it locks into place.
If the new bulbs do not work
Check your fuses
If the fuses are fine
Check or replace the relay fuses big box looking fuses on the small fuse box to the left of the front left headlight.
Determine which headlight(s) is not working.
Purchase a replacement bulb(s).
Turn off the car and headlights.
Open the hood.
Look inside the hood directly behind the headlight that does not work.
Grab the bulb and casing (an L shaped tube) and as you are facing it rotate it clockwise about 1/8-1/4 turn until the notches on the bulb align with the grooves in the headlight fixture's opening.
Pull the bulb out out the headlight fixture.
Depress the plastic tab on the plastic connector and remove the bulb from the wiring.
Insert the replacement bulb into the plastic connector and press into place until the tab snaps into place and the bulb is firmly connected to the wiring.
Insert the new bulb into the round opening of headlight fixture by aligning the notches with the grooves on the fixture.
Rotate the bulb counter-clockwise until it locks into place.
If the new bulbs do not work
Check your fuses
If the fuses are fine
Check or replace the relay fuses big box looking fuses on the small fuse box to the left of the front left headlight.