First, make sure the Volume is turned up on BOTH the Cable Box AND the TV. Each has its own independent volume control and if one or the other is turned down, then you will have no sound.
Beyond this, please reset the system by following the steps below:
Please shut the TV and cable box down. Unplug the Cable box from AC power for minutes. During this time, disconnect and reconnect the HDMI cable on both ends, making sure it is secure. Then plug the cable box back in, turn on and let it reboot. Once it's rebooted, then turn on the TV and attempt to watch a program.
The sound should be back on at this point.
If you need further assistance, let me know.
How long have you had the set for and when did the problem occur?
Also, what is connected to the TV for devices (Cable Box, DVD, Game system, etc.), and do you get NO sound on the TV regardless of which you're watching?
Do you have a DVD player connected to the TV?
If so, please check it and see if it produces sound on the TV.
Sorry, I meant cable not dvd.
Did you attempt to reset the cable box EXACTLY as I had described?
Also, if you turn the TV volume up all the way, do you hear any hiss, or buzz coming from the TV speakers?
Thanks for the reply. This indicates that the audio IC that drives the internal speakers has failed. It is common in these sets as they use very cheap, low powered amplifier IC's that generally heat up and fail. This type of repair is typically around $200 to replace the IC. A workaround, that is less expensive and also yields better quality than the original speakers is to use a set of self-amplified external speakers that connect to the "Digital Audio Output" jack of the TV.
Here is a link to the speakers I would suggest below:
Or, if you'd like to have the amplifier IC replaced in the TV, then you can locate a tech at the link below: