Ok
by the numbers
Check the fuse
check the dimmer switch.
If you are going to check things yourself you should have a good test light.
Good ones cost around 10.00 or more but are worth it.
This is the one I use.
http://www.napaonline.com/MasterPag...PartNumber=7001437&Description=Circuit+Tester
you hook the clip to a good ground and use the point to check the wire. When there is elecricity in the wire the tester will light up.
The main thing you use it for is to make sure electricity is getting where you want it when you want it there.
It would help if you could tell us what year and model of car you have.
Some of us are more familiar with some models than others.
The older cars are pretty easy to check and the new ones can be a real pain.
The main thing is to make sure that the fuse (s) is/are good. the connections are good, The bulbs themselves are good.
If they just quit it is usually something simple and easy to fix.