Bad,

It's hard to know what's amiss without checking out the TV. It might be a simple board or component replacement, but maybe not. You should troubleshoot completely before having the TV opened up by a qualified repair person. Did you happen to change any of the settings, like turning off the internal speakers? Did you somehow lose connection with an external receiver? Are all of the TV's audio settings silent, or does the plain vanilla stereo still work? Did you mute the sound and forget about it? Don't laugh; stranger things have happened.