I want to go back to windows 8.1 on a asus m551x but windows 10 upgrade deleted factory reset and i dont have a disc.

[tbone2015]

factory reset no disc after windows 10 upgrade

 

[basroil]

Just follow the instructions at http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media

Before you use the installer though, make sure to have a copy of all the drivers just in case you need them during install (particularly the storage controller driver)