going to assume you have done all the obvious (ie workshop, sound settings)
if you disabled sound in overides,,you get the meow, and the drums etc, but no sound in the game.
and, this is just a guess, it has solved some pretty quirky problems in my game
go to c:\documents and settings\administator(this is where it is on mine,,,it might be under your username on yours)\application data (appdata if you are running vista)\microsoft\cfssww1 overflanders fields, find the uisel.xml, and copy it to a safe place, This is just a safeguard, you can delete this file, and when you start off it will regenerate the file. now delete it, and restart your game. there is a sound on setting in there, so who knows, it might fix the problem.
like i said,,,just a guess