in the BIOS.... you will need to reboot, and during the POST hit the delete key, once in the bios look for Integrated Peripherals option, and in there you should have the option of enabling onboard sound IF you have it(its very common so you probably do). Save and exit bios and once in windows it will tell you it found new hardware, install
drivers. If you happen to know the make of your board we can the latest drivers before we do anything else