Yesterday I installed the technical preview of W10 on my SP2,obviosly I made a recovery drive on a USB before. Now I want to go back to windows 8.1 but the recovery drive I made is not working, when I select which OS I want to restore in the boot menu "Windows Technical Preview" always appears but not W8.1,so It keeps reinstalling the preview. I even tried downloading a W8.1 ISO file to see if I can install it and go back to my recovery drive using it, but every time I try to reinstall windows 8.1 the installation goes way too fast to end with the "There was a problem installing windows 8.1" message appearing after a while every time. I disabled Secure boot and all and it doesn't works. So I'm stuck with windows 10. What I can do to reinstall windows 8.1 on my SP2? I was thinking about installing Ubuntu and from there reinstalling W8.1,is that a good idea?