If your Vizio TV is not playing sound, there are a few potential causes. First, check to make sure that the volume on your TV is turned up and that you have not muted the sound. If the volume is turned up and you have not muted the sound, then the next potential cause could be an issue with the audio settings on your TV. To adjust the audio settings on your Vizio TV, go to the menu and navigate to the audio submenu. From here, you can adjust things like the bass, treble, balance, and other sound settings. If adjusting the audio Settings does not fix the problem, then another potential cause could be an issue with your HDMI cables or with your HDCP (High-Bandwidth Digital Content Protection) setting. To check if your HDMI cables are working properly, unplug them from both your TV and your device (e.g., Blu-ray player) and then plug them back in again. Make sure that they are firmly plugged in at both ends. If you still don't hear any sound after doing this, try changing the HDCP setting on your TV. To do this, go to Menu > Settings > System > HDCP Mode and change it from Auto to Off.