What would cause both headlights to go out at the same time (HD lights)? on 2006 Infiniti M35

What would cause both headlights to go out at the same time?
(HD Lights)high beams work.

Was told I need to have whole system replaced, which includes
bulbs,ballast,etc

1 answer
its ur ballast but just buy the ballast and the start up wire because that loses power too...