I'd download the Windows 10 .iso and burn it to a DVD or make a USB-stick from it.
https://www.microsoft.com/en-us/software-download/windows10 tells how.
Then let it repair.
That's the common way for people who used Windows update to upgrade in stead of downloading the full installer themselves.
Hello! Here's what happened : my computer had hardware problems, so I backed up images of my drives and got it repaired. It used to be on Windows 10 but they restored it to factory settings and Windows 8.
I then tried to restore the image of my drive containing windows 10 (plus my programs, files, etc) but when I then booted my pc, Windows wouldn't start and would ask for a recovery disk which I don't have.
So where did I mess up? Could you help me recover my pc, hopefully in the state it was when I backed it up?
Thanks in advance!
EDIT : here's the message that I get when I try to boot : https://goo.gl/photos/FZsmznuLuuUhuT6P9