Many things can go wrong when hooking up your home theater system to your HD TV. Poor audio connections, muted electronics and even television settings can all contribute to the loss of sound. Ultimately, if you can not resolve the problem, check your warranty on your unit and have it serviced.
Check the Mute Button
Check to see if the mute button was pushed accidentally on your remote control. This is a common problem and is very easy to fix. Press the volume up or down button to see if that fixes the issue. You may also have the mute button pressed on your audio equipment. Checking this issue first will allow you to troubleshoot other problems.
Make sure during the initial setup of your Sharp you do not have the "variable" option selected as your output mode. The output select function allows you to control which device generates your sound. If you have connected a home theater system, you need to choose this as your output variable. This function will mute your television's speakers and push the sound through the sound system.
Connecting your audio cables wrong will cause the television to not have sound. Go back and look to make sure that your audio connections are connected into the S-Video connectors. The wires for audio are usually red and white. Connect these cables to the corresponding colors on the back or side of your television. If all else fails, your television may have either a faulty sound board or driver. Contact the manufacturer so they can service your unit.