If your gas fireplace is not igniting, several issues could be the cause. First, check if the pilot light is out, which is a common reason for ignition failure. Ensure the gas valve is fully open and that the thermocouple or thermopile is functioning correctly, as these components help detect heat and control gas flow. A clogged burner or debris around the ignition system can also prevent proper ignition. If these checks don’t resolve the issue, it’s best to call a professional technician for a thorough inspection and repair.