To troubleshoot a Sharp TV that loses sound, increase and decrease the volume, and check if the mute button is pressed. Make sure the Variable option is not selected as the output mode if no external speakers are connected. Also, check if the audio cables are connected properly.
If the volume on the Sharp TV is reduced, increase it using the volume controls on the remote. Typically, the mute feature on the television shuts off automatically after 30 minutes, but this does not restore volume to its previous setting.
If a home theater system is connected to the television and the Variable option is chosen as the output mode, this mutes the television speakers in order to divert sound through the theater system. For a Sharp TV not connected to the external speakers of the system, select Fixed as the audio option under Output Select on the TV menu.
Check if the red and white audio cables of the television are connected to their respective colors on the S-Video connectors behind or on the side of the television. If none of these steps resolve the sound issue, the driver or sound board may be at fault. To fix this problem, get the television serviced by the manufacturer.