Could you get the model number form the back?
Do you want to fix the TV?
If you unplug you TV and the sound come back on. The e prom will need to be replaced. You will need to unsolder and re solder the chip in. Please be very careful inside the TV. Even with it unplugged it will have power in it.
I would need the service number and the chasis number for the part number.
If you can't get somebody to come to your house. You don't have to take the whole TV into a shop. RCA has a box inside that the whole chassis in that come out. Then you can take the box into the shop.