While watching tv the sound went out

i found something on internet for your problem.
please check this,

http://removeandreplace.com/2017/03/13/tv-power-light-comes-on-but-no-picture-or-sound/

backlight may have gone if your tv has one

please see your other post for response

Check and replace the main power regulator board as card basis. It has damaged.

I WOULD SAY NO ! THE PICTURE TUBE IS PROBABLY AS MUCH AS THE TV IS WORTH. i had a very nice sony trinatron tv. the picture tube whent on it at about 5 years so I CALLED FOR REPAIR AND THE PICTURE TUBE WAS 2-300 DOLLARS. good-day !

Sound comes from the main board, I would say it has issues and needs replacing

if theres nothing at all (sound and vedeo) then the power supply section may check, fuse, power I.C. or transistor

we had a similar problem on our 40 inch samsung , the screen went black but we could still hear sound on ours it turned out to be the main board not the inverter like some people liked to think thanks

That probably happened because something hit the TV and broke the line for pictures to get through, or because a wire in you TV is bad and doesn't wanna work. This happened to my TV every few days. What I did is give it a few whacks every now and then on top of it and the vision came back, but don't try that if you think your TV is fragile. Yes I know its sounds stereotypical but it actually sometimes works.

Well, good luck!

Sounds like the Power Supply on the TV went bad.