though itz unclear to me of wat os u r using..
assuming that u r using win xp pro sp2..n directx installed..
check if Audio device is enabled in bios..
howevr,download microsoft kb888111update n install it..u need to re-install orupdate the device driver (may b manually)..logon to internet n seek thepackage/device driver..along wid the company, there will b a list of suchsite n driver download links if u search by the model name on a searchengine (like google)..http://www.asrock.com/MB/download.asp?Model=P4i65G&o=XP
download themonto a location; if the driver is in a zip format, unzip it,if itz in.exe form, just run it; if done manually it'll ask for the correctdriver and location; relocate the path and a.inf file (wat it'll askfor)....goto the device manager n verify, if installed properly..!!
also download n install "k-lite mega codec pack"....
but always better to consult ur system admin/vendor....