A fully functioning headlight is a legal safety requirement on your vehicle and is the kind of component that will be checked as part of an annual MOT.
A disproportionate number of traffic accidents and fatalities occur in the dark in relation to the number of journeys taken. It is a similar story during other periods of lower visibility such as when travelling in rain or mist.
A malfunctioning headlight must be replaced immediately. A quick search or phone call should reveal a wide range of high quality

headlights

for every make and model of car.