1. try a new bulb
2. try checking the wires/elctronics
Not sure what vehicle you have but check the fuses. Some vehicles have separate fuses for left and right headlights.
You change the bulb for the right headlight the exactly same way as you changed the left only opposite. If you are replacing one headlight, even if the other still works it is best to replace them in pairs, for lights can dim and if you have a bright bulb and a dim bulb you could be in danger of distracting other drivers and causing an accident.
The fuse box is located below the dashboard to the left of the steering wheel. Right headlight (10A) position 1 upper right corner. Left headlight (10A) position 2 just below it.
One works with left hand, other works with right hand
On a left hand drive vehicles, it is on the front right side behind the right headlight
Open the hood, and its right there behind the left headlight.
This depends entirely on left or right, year make and model of car
right side adjusts left or right left side adjusts up & down
open the hood and look on the driver's side right by the left headlight.
Behind the bumper underneath the left headlight, except for the 4-door and the 1.8L models, where it is underneath the right headlight.
Just take it to a car mechanic. You can't exactly look at them at the same time, so if a car has this problem, you should take it to a mechanic; it may cost a bit, but it's better than trying to fix it yourself and end up screwing both sets of lights entirely.
in your WHEEL ARCH at the back of the headlight there is a little hatch, open it and you'll find your bulb. eg. if your right headlight has blown, turn your steering wheel to the left for easier access