This led no picture but sound ok back light ok

Abdul Samad try this first. Disconnect the set from the AC Power. Press the power ON the TV (do not use the remote control for this) for at least 10 seconds. After a minute plug the set back on and click power once. See if this will work.

If that does not work it is possible that you have issues with either the power board, the main board or the T-con board. You will have to remove the back of the set and take a look at the boards, check for obvious damage like leaking or domed capacitors. If you can, post some pictures of your boards with your question. That way we can see what you see and possibly help you further. Use this guide Adding images to an existing question for that