can u get any sound? beep on startup or otherwise?
I have had probs with sound drivers and start by building up from a generic such as sound blaster.
if no sound on start up then the sound system is us! If u get a beep on start up then the sound sys is ok.
try (and I'm sure u've done this remove soudn drivcers and see if on start up you can get anythng through the sound system in control panel. if so the geneic windows drivers are working the system. if not then all I can suggest is go to DOS (yes very ancient and try such things as CTRL G (I think) and iot should sound the beep! If not then electrical fault...