It is really unusual that you retained the picture part after the lightning strike, but what is wrong now is in the audio portion of your tv (obvious). However, if you have not taken the back cover off already it could be as simple as a blown fuse in the low voltage power supply or just blown audio amplifiers due to the sudden voltage and current surge caused by the lightning. The fact that you can get your audio through your surround system kinda narrows it down to the audio amplifier section. Just take the back off and look because those size tvs do not have alot of boards. All in all see if the problem is visually obvious like a fuse, because with out taking actual voltage measurements it could be a couple of boards in there causing the problem. Good luck and let me know. God bless you. Robert