You can get the High Definition Audio drivers from the Realtek website. However, there is another way to install them. In most of the the download from the Realtek will not work properly with your chip. In this case, first identify if you have an on-board audio device. You can check at the back of your computer.
Once identified, it means the driver is found on the Support CD for your motherboard your can browse to the manufacturer's website and download the appropriate driver.