A tad more information would be nice.
a) Do you only have no sound in STO or in general?
b) What's your sound card?
c) Did you update your drivers for your sound card?
d) Are your speakers turned on?
e) Do you have another sound-using application running at the same time (Skype, Ventrilo, winamp, iTunes, etc...)
Give us more information and we might have an easier time helping out.
I'm in the same camp here. Yesterday, sound was fine. Today, it's gone in-game only. All other systems have sound just fine (media player, other games, etc)... at first, I thought it was my mistake, as I'd just gotten a new desk and had to unplug everything- thought I had the audio jack in the wrong port, but nope.
Logged out and exited completely... logged back in, and I'm fine now though.