First check the bulbs to be sure they are not bad. Then check the fuses, some vehicles have a seperate fuse for each light function.
High beam light is out!
You Have a bad headlight, it's common when a headlight burns out for only the high beam to work, solution change your headlight.
There are separate fuses for each headlight, they should be in a fuse box which is normally located under the bonnet.
bad light switch.
adjust headlight beam on 2010 xtrail
headlight switch is probaly your trouble
Use a 12 volt tester and turn thr lights on and see if you have power, then make sure the bulb is a high/low beam.
Probably the low beam filament in the dual beam headlight lamp is burnt out. See sources and related links below for more information on the headlight lamp.
TRY CHECKING TO SEE IF YOU HAVE A HIGH BEAM HEADLIGHT OUT. tHIS WILL CAUSE THE PROBLEM YOU HAVE.
9006 for the low beam 9005 for the high beam
There are three headlight settings on your headlight switch. You can turn the low beam headlights on by turning the headlight switch.
Begin by removing the wiring harness from the back of your 1989 Silverado headlight assembly. Remove the low beam headlight assembly retaining bolts. Reverse the process to install your new low beam headlight.