To diagnose a sound problem on a Vizio television set, check that the volume is turned up above zero and the television isn't muted. Check to make sure all of the cables that are connected to the television are inserted securely, including those from any input devices.
Go to the Audio menu on your television set to make sure the TV speakers are set to On. If you are using the built-in TV tuner, check that all audio cables are secure, including the antenna's, and make sure your antenna is in a clear, open area. Open the MTS Audio menu, then the Tuner menu, and make sure the setting is on Stereo/English.
If you have any other devices connected to your television, such as a DVD player or a game console, turn a device on and switch to it using your television's input function. Confirm whether the sound works when using the peripheral device. Switch the cables around to see if the audio from the device still works the same. If not, the cable may need to be replaced.
If you are using an external audio system, cable or satellite box, check the volume settings on the device and adjust them accordingly if they are set to Low or are muted.