No Audio in my Vizio HD TV

Same happened to me us this morning.... we had sound the night before, no one touched anything, but we finally figured out to go to (on the Remote Control) MENU, scroll down to SETTINGS, choose the 1st option SET-TOP BOX VOLUME, we hit OK to view your set-top box volume. On the screen there was on the top right a visual of our setting and it was 'red' and looked to be none or mute. We hit the up/down arrows on the remote to change the none/mute to 14 and we had sound. WEIRD, VERY VERY WEIRD that it reset itself, but this is what fixed our problem. But first I did unplug and reset all boxes attached to the TV for about 10 minutes. Same happened to me us this morning.... we had sound the night before, no one touched anything, but we finally figured out to go to (on the Remote Control) MENU, scroll down to SETTINGS, choose the 1st option SET-TOP BOX VOLUME, we hit OK to view your set-top box volume. On the screen there was on the top right a visual of our setting and it was 'red' and looked to be none or mute. We hit the up/down arrows on the remote to change the none/mute to 14 and we had sound. WEIRD, VERY VERY WEIRD that it reset itself, but this is what fixed our problem. But first I did unplug and reset all boxes attached to the TV for about 10 minutes.