I don't have specific info on this model, but if this is a direct view LCD TV, most likely the problem you have is caused by a defective Digital Main board.
There are basically 3 things in an LCD TV: the Power Supply, the Digital Main circuit board, and the actual LCD screen itself. The screen probably isn't suspect because a falure doesn't usually cause your problem. The power supply isn't suspect because the stand-by light comes on, indicating there is power to the Digital Main.
That leaves the Digital Main, which does all of the signal processing necessary to display video on the screen, as well as controlling the sound and picture functions.
The Digital Main board can't really be repaired, because it's so densely packed with micro electronics that were machine assembled at the factory, so the entire board would need to be replaced.
If you are at all handy with electronics, you should be able to replace this board yourself, and if you'd like to try that, let me know and I can give you some pointers, but I don't know who supplies parts for your set.
Hope that helps, and thanks for using JustAnswer!