Download the Realtek Audio installer on the link given below this post and save it to your Downloads folder.When done, hold down the Windows key and press R.
Into the Run window type devmgmt.msc and hit enter.
In the Device Manager window, expand Sound, Video and Game Controllers. Right click the Realtek device and select Uninstall - you should also get a prompt to remove the current driver, tick the box to allow this and then proceed with the uninstall.
When complete, download and reinstall the Chipset driver on the link given at bottom.When the Chipset reinstallation has completed, restart the notebook.
When windows has reloaded, open your Downloads folder, right click on the Realtek Audio installer and select 'Run as Administrator' to start the installation. When this has completed, restart the notebook again and let Windows fully load for a few minutes before checking.
Download Realtek Audio Driver Download Chipset Driver