I recently got windows 10, but I decided I want to go back to windows 8.1. I tried going to settings, then update and recovery, but it said that it had deleted the necessary files to revert. So I then got my windows 8.1 64-bit disk and ran it, an when it was about to start installing, it told me that it couldnt determine how i wanted it to setup, even though I never really chose anything like that. So then I tried again, this time choosing to install any updates which was recommended, and it said that Windows 8.1 Installer needed to restart before it could work so I waited 15 minutes and nothing happened. I need help getting back to Windows 8.1

It says Something Happened and it cant determine my install choices or it will say it needs to restart, which it doesnt do