dash board lights won't turn on...

Hello all,
I have a Golf 2002 2000cc. when I'm turning the the lights of the car on, no dash board light turns on (main display and also climate control and window buttons),
It's strange because if the head light are off, the back light of the lights knob works' and the head light turned on, it goes of (maybe it's should be like that?)
What is the problem?

Maybe the problem remains on the switch. Usually the switch itself is the dimmer control as well, so turn the dim control up so the lights can come on. Sometimes that dim control gets bad and you need to replace the switch in order to bring them lights back, specially if you mention that the switch backlight works, but with the headlights on it goes off, this also tells you that it ain't a blown fuse. If you still have the factory radio, and it is supposed to dim along with instrument panel lighting, then I'm quite sure it'll go very or absolutely dark.

Other thing is having a current tester, this thing looks like a screwdriver with a cable hanging out of it and a light bulb inside its handle. This can be very time consuming and more difficult to do, since you have to find the cable or pin on the switch that carries the lead current to the instrument lighting. If you get it, you need to clip the tester cable to a good ground spot on the car (a bare metal spot, the head of a screw, a nut or something that is bare metal, no paint) and then, with the tester, touch the cable (you need to strip it a little bit if this is the case) or pin that carries the lead current to the dash lights. If the tester glows, then you have a ground problem. If not, a new light switch will call it a day.

Due to the large amount of bulbs not working, and because they are grounded to different places, I sincerely doubt that there is a ground problem, and the switch may be waiting to take the responsibility of your problem.

Thank you very much!
It was the dimmer switch as you assumed...

It was fixed in no time and I've got dash board lights again...

No prob cousin, we're here to help