The quick test for this is to press the menu button on your remote. If you are unable to see the menu appear then the TV will require service. Here's the thread where you can get details on setting that up: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
I have a samsung lcd tv model:LN46C600F3FXZA and i was watching tv and all of a sudden my picture went but i still had sound. I looked up possible problems and replaced the inverter board but i still cant get no picture only sound.