Your laptop should have come with either installation media or a "hidden" factory reset partition on the hard drive. If you don't have reinstall media and you wiped the partition when you installed the "fake OS", then your only option would be to contact your laptop manufacturer and download/purchase the reinstall media.
You can *try* and get a Windows 8.1 ISO from Microsoft, but since your copy was OEM from the laptop manufacturer, you might not be able to.
-Wolf sends