I just had the same problem with a friends monitor.
The problem can be one of 2 things:
1) One of the bulbs in the monitor is bad
2) The inverter board in the monitor went bad (most likely)
A quick way to tell if it's the inverter board is to turn on the montor then use a flashlight and point it directly into the lcd screen (keep it about 10-12 inches or closer from the screen) you should be able to see your O/S (or "no signal" if the pc is turned off).
The inverter board (in a nut shell) directs power to parts of the monitor at voltages they require to function.
As far as what to do with the monitor;
1) If the monitor is still under warranty, call the manufacturer and get it serviced
2) If the monitor is old, it might be cheaper to replace it (price for parts and labor might out weigh a new monitor)
3) If it is out of warranty but is still in very good shape, you can call the manufacturer or local service technicians for prices to repair it.
I had a Envision 17" LCD montior in my case. Envision quoted me $45 + shipping = $51 for parts and installed it myself (process takes some technical savvy).
good as new
Hope this helps....good luck
Edited by jonnyb, 09 March 2008 - 09:34 AM.