If your TV isn't producing any audio, verify it's in the correct input mode, and increase the volume of the TV. If it still isn't audible, toggle the Mute button on the TV remote. Next, check whether there are headphones connected to the Audio Out port on the side or front of the TV. If there are headphones present, disconnect them.
If the TV's Secondary Audio Protocol setting is enabled, disable it. Do the same if it the Simulated effect is on. Next, access the TV's settings, and verify the speakers are set to On. Additionally, ensure the TV speakers aren't set as the center speaker. If there is still no audio, press the Reset button on the TV to set it to default factory settings. Perform a hard-reset if there is no Reset button.
If the TV is connected to an external device such as a cable box or DVD player, turn it off, and turn it back on, and verify that the audio connections are firmly and correctly set. Next, go to the device's menu, and ensure the sound settings are set correctly set. With the volume on the TV turned up, increase the volume of the device. If there is still no sound, test the TV using a different external device.