Ballast, cables, fuses, connections in general?
Which car? 3rd party install I guess?
If the bulb is fine and the fuses are okay, the likely culprit is the ballast/exciter. A lot of people buy cheap, this is the sad outcome.
If it's an aftermarket kit, a ballast won't be that much.
Have you any pics of the kit?
If it's an aftermarket kit, a ballast won't be that much.
Have you any pics of the kit?