By default the Linux kernel that we use should include all Realtek drivers. However, if your card is one of those exotic types that does not detect, try this:
RealTek Driver Page, Pick the 3.0 driver.
Type: “sudo su” and enter root password.
Change to the folder where you downloaded the driver (ie: “cd ~/Downloads”)
Type: “tar -xjf LinuxPkg_XXX.tar.bz2” , where XXX is the version of your downloaded driver (as sown in filename, example: “tar -xjf LinuxPkg_5.17rc13.tar.bz2”).
Type: “cd realtek-linux-audiopack-YYY” , where YYY is the version of your downloaded driver (as shown if folder name, example: “cd realtek-linux-audiopack-5.17”).
Type “tar -xjf alsa-driver-ZZZ.tar.bz2” , where ZZZ is the version corresponding to the filename (example: “tar -xjf alsa-driver-1.0.25-5.17rc13.tar.bz2”).
Type “cd alsa-driver-WWW” , where WWW is the version corresponding to the folder name (example: “cd alsa-driver-1.0.25”).
Type “./configure --with-cards=hda-intel”
Type “make install”
Test the audio output. You can do this by right-clicking on you speaker icon and selecting sound preferences -> hardware -> select the desired audio output -> select the desired surround profile (ie: Analog Surround 5.1 Output + Analog Stereo Input) -> Test Speakers. During the installation the sound level can be muted, check out in the slider if it is not mute!