http://bugs.winehq.org/show_bug.cgi?id=20021
--- Comment #3 from Ciaran 15094014@sun.ac.za 2009-11-17 18:49:38 --- Changing sound device to headphones brought my sound back, it was on speakers 5.1. I had no headphones plugged in and haven't tried the other modes but I assume a few of them will work too.
I haven no idead if this is a wine bug, pulseaudio or l4d bug