It sounds like your backlight is out or barely functioning. Try replacing the inverter board(s). Since you can see a picture, the T-Con board is probably okay.
More than likely your t.v has bad capacitors that power up the light bulbs that light up the screen. I had the same problem with a similar t.v. and replaced two bad capacitors and that solved the problem. Take the back off of the t.v. and look for capacitors that are bulged at the top. The capacitors have the model number on the side. I found replacement capacitors at www.digikey.com for a very low price. Here is a video that you can watch on how to replace the capacitors. https://www.youtube.com/watch?v=YCSNWi3UHf4
It sounds like your tv is in sleep mode. What are the settings for the computer? Make sure it is set for the vga output. If it is a laptop, this is usually done with a function (FN) key. On your settings screen you can set the resolution and which monitor you are using.
The tv power supply board it is the cause and the problems.That the board,where the power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a refurbish power supply board for the replacement.
Tries tv unplug,replug it back like about an hour later.The tv now,it is resetting itself back to the tv factory setting.The tv should work now,if not still have the same problems.Than the tv power supply board is the causes and the problems.That the board,where the power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole rrefurbish tv power supply board for the rreplacement.
