Internal Display not working, external is.
I am having a similar issue with a 2010 iMac 21.5".
I can get an external monitor to work fine (I'm actually using it now).
I have tried resetting PRAM and NVRAM with no success.
In system report under Graphics/Displays, I can only see my external monitor connected via Mini Display Port adapter.
I have tried looking at the screen with a flashlight (torch), i cannot see any forms of life.
Is this a good question?