If you take out both your headlights underneath is the ballast of the headlights and theres just 3 screw and just swap them out, also check for shorts inside the box. My Ballast just went out not that long ago in my car as well and its an 04 too. It cost me a little more than $300 new but don't have anymore issues.. Good luck!
2013 Nissan Nismo 370Z - Current
2004 Non-M Facelift Coupe - Current
2006 BMW M3 - SOLD