got sound no picture

Is it the problem with the black screen? If it is, hold the power and the home button at the same time for about 10-20 seconds until it turns back on. If not what you meant, tell more detail.

If your set is a Plasma model, you might want to check the x buffer board. Again, check out the videos available on You Tube; I call it You Tube University. You may find a video that will help you solve your problem.