Philips Flat Screen TV has sound but no picture and on light is green. Tried reconnecting cables but this has not worked.

Is it just the cable? Do you have a DVD player or game system connected? If so, how do they look? Ofter a momentary power loss can cause cableboxes to loss picture, loss sound, and even cause the picture to be distorted. Try unpluggind the AC power from the cablebox and TV. Wait about 5 minutes and reconnect both. Leave the cablebox alone for about another 5 minute after you reconnect it so that it can fully boot up. Then see if you still have the problem.

internal breaker, hopefully that xbox is plugged into a 3prong ac outlet. unplug the tv from electricity for a half hour and that circuit breaker inside should auto reset.

When the screen goes completely black, shine a very bright flashlight closely at the screen. If you can see the image, then the most likely problem is that the backlight inverter has failed.

The inverter is a circuit board that works like a flourescent light ballast. If the inverter fails, there is no backlight, and the screen is black.

Since the invertor is a high-voltage component, I would also listen for any unusual sounds associated with the failure: e.g. buzzing, whistling, popping.

To rule out some sort of connection failure, see if you can recreate the failure mode when using the TVs internal setup menu. The setup menu does not rely on any external inputs....of course neither does the volume control or channel indicator on the screen.

control boards on LCDs and PLASMA tvs are causing no picture , missing area , and other wierd symptoms , it will need to be tested to determine the true problem

Your backlight finally went out. If doing it yourself, you need to order 2 to 4 backlights along with an inverter. It is good to replace both at the same time. The backlights are like mini floresent tubrs that need to be taken out and replaced by some one who has done it before. The cost will run you about 50.00 if you do it yourself.
Take care
Kevin

Philips 37PF7320A 37 no power but the green light is on

TV STARTS UP AND GOES BLANK SOUND NO PICTURE

The problem is the small signal board that is the video processor.

Have you tried disconnecting the power from the wall? Or power cycling your entire entertainment center? Possibly even check to make sure the VGA cable (or any other cable) didn't somehow come looose?