My headlights and cluster are nt working war can it be ???

Year make and model Please. Head lights could be a bad light switch. could also be a bad turn signal switch. The cluster, If other lights come on, IE.. radio, hvac control. Then it could be a bad wire or bad connection at the plug. Could also be a broken connection in the cluster(older ones had a plastic cover with leads in them) (newer ones could be a bad solder joint).

Since your question doesn't include make and model the answers given will likely be generic in scope.

If you have a light switch on the dash or if it's on the steering column it could be either the switch itself or you may want to start with the battery lead and ignition leads to the switch. A bad dimmer will cause problems with the instrument cluster lights but that gets its power from the light switch. While it is a long shot, you can check fuses in all fuse boxes, generally one under the hood near the battery and one under the dash near the driver. Fuse issues come about after an accident involving damage to any of the outside perimeter lights and can include wiring damage as well.