My philips flat screen HD Tv turns on but does not show image?

I have a 2006 Philips HD Tv that does not show image. The lower left light indicates the tv turns on but the screen remains black. I dont know if theres a problem with the screen. I was told it might of gone into protection mode. How can I find out if it is on protection mode or if the screen is blown. As of now I dont have any image and it clicks when powered on. No flashing red lights on the power indicator only green. Can anyone help?