downlaod sound driver
from this HP compaq site
: (it's the first link "Audio-driver")
try to install and see if that works.
if not then:
open device manager
and right click on unknown device
(which is you sound card) then properties
click on details
tab and hardvare IDS
in dropdown list,
now copy all and paste here.
it looks like this: USB\VID_04F2&PID_B008&REV_9327&MI_00
using that info we may be able to find driver for your soundcard.