Final answer:
In case of headlight failure, one should immediately activate their parking and hazard lights and safely exit the roadway, then seek assistance.
Step-by-step explanation:
If your headlights fail, the safest option is to turn on your parking and hazard lights and exit the roadway immediately. This will alert other drivers that you're experiencing difficulties and provide some visibility while you safely get off the road. Continuing to drive without headlights is dangerous, as you'd have decreased visibility and other drivers may not be able to see you. Follow this action by contacting emergency services or roadside assistance for help.