Why do I have sound but no picture

Lori Slotsky  sounds like a bad backlight. In a darkened room and the TV on a channel where you do hear sound, shine a flashlight beam at an angle against the screen. See if you can make out shapes or silhouettes. If so, it’s your backlight. Possibly a failed backlight strip or possibly the power board. You will have to remove the back cover from your TV and take a look at the boards. Better yet, post some good images of your boards with your QUESTION so that we can try to guide you some more.

Adding images to an existing question