I'm sorry to hear that you're having this problem.
So the way I read this is that there is no sound, regardless of the input. I don't know if this model has the same reset features that some of the more recent sets have, but it may be worth trying (unless your set is professionally calibrated, since what I'm about to suggest will reset the settings)
Try, with the TV on, holding down the EXIT button on the remote for about 15 seconds to see if you're prompted to (RESET?) and if you are, click YES and see if your audio comes back.
If that doesn't work, I might try to see if the audio out jacks on the back work. If you have a receiver or a small radio with an AUX IN jack, see if connecting that to an RCA cable works. If not, the board with the audio controls may be bad.
I have a LN-R328W Samsung LCD TV. Recently I turned on my television and the TV displayed the setting STD 2 SAP. I am using a cable box. I then put in a DVD and then the picture appeared but no sound as well as when I plugged in my game system. The internal mute is not on and I really don't know what to do.