Sorry if I'm posting in the wrong forum, if I do so, please move it to the right one.
My main OS is Windows 7, but yesterday I installed Windows 10 Insider Preview so I can dual boot. But something went wrong, I think the image was corrupt, because windows was not booting anymore. And neither was Windows 7. Both were stuck at the booting screen. So I inserted my Windows 7 install and I deleted the windows 10 partition, but 7 was still not booting. I ran startup repair, no luck. Ran a command prompt window and tried to import my registry backup, because I think that the registry is causing all the errors, but it failed, telling me that registry could not be accesed. So on that blank partition left by Windows 10 I installed another copy of Windows 7, which I succesfully booted into. I tried importing the backup now, same error. And nothing else worked. Cmd, Internet Explorer, all were exiting with an error, something about the side-by-side configuration being incorrect. So I rebooted and this time I couldn't even enter it, saying something like "Interactive logon failed".
Can you please help me?
EDIT: Nevermind, I solved it. Booted into the repair your computer mode, ran a chkdsk and then bootrec.exe /fixboot and /fixmbr
EDIT 2: At boot, I still have to choose between two Windows 7 options, although I deleted the other partition. So I still need help

Edited by Pufi, 10 June 2015 - 09:13 AM.