LG Plasma televisions allow you to reset the picture and the audio separately. If you have changed the sound and picture settings, and wish to restore them to factory defaults, you can do so using the TV's remote control. Once you have reset the codes, you can change the settings using the remote.
Press the "Menu" key and scroll down to "Picture."
Press the "Enter" key and scroll down to the "Screen (RGB-PC)" option.
Highlight "Reset" and press "Enter."
Select the "Yes" option and press the "Enter" key again to reset the picture.
Press "Menu" to exit the menu.
Press the "Menu" key and select "AUDIO."
Press "Enter" and highlight "Reset."
Press the "Enter" key to reset the audio.
Adjust the audio settings to your preferences, then press "Menu" to exit.