Make sure that you do not have the TV muted and the volume isn't at the lowest setting. If there is still no sound look behind the TV to see if anything is plugged into the sound out. Having something plugged into the sound out sometimes turns off the sound in the TV's built in speakers. Also go into the sound settings and double check that the internal speakers are not disabled, or that the tv is not set to audio out only. Next make sure that you have the audio cables correctly connected, or if you are using HDMI, there are no audio cables to worry about. Make sure the sound cables are also connected correctly to the device that the signal is coming from. If you did all that, check to see if your device is outputting sound in the first place. Go into the settings on your device to see if the sound is disabled, and that the output you are using is the one being used for sound output. If all of these steps don't work you should take your TV into a repair shop to be fixed.
Answers & Comments
Make sure that you do not have the TV muted and the volume isn't at the lowest setting. If there is still no sound look behind the TV to see if anything is plugged into the sound out. Having something plugged into the sound out sometimes turns off the sound in the TV's built in speakers. Also go into the sound settings and double check that the internal speakers are not disabled, or that the tv is not set to audio out only. Next make sure that you have the audio cables correctly connected, or if you are using HDMI, there are no audio cables to worry about. Make sure the sound cables are also connected correctly to the device that the signal is coming from. If you did all that, check to see if your device is outputting sound in the first place. Go into the settings on your device to see if the sound is disabled, and that the output you are using is the one being used for sound output. If all of these steps don't work you should take your TV into a repair shop to be fixed.