Go to the driver page of the G551jw download the realtek driver if no W10 driver download the W8.1 realtek driver do not install as
of yet do this first
Go to Device Manager, find "Sound Video Game Controllers" remove the Realtek audio driver
Then install the realtek driver u downloaded
http://www.asus.com/Notebooks/G551JW/HelpDesk_Download/if still no sound search for "sound control panel "select speakers as Realtek High Definition Audio as default device