Take a fresh install of windows, update, restart, update, restart,....
On some machines it says "this update couldn't be installed", after a fresh windows installation.
For win 8 you have to turn to the shitty shop (or is it called market?) to install win 8.1
Windows Update is a horrible nightmare, to my disappointment they still don't kill it and make it better.
btw, has anybody tried updating a windows phone? What a f*ck. "downloading update", "preparing update", "updating", "restarting", "after update modifications", 30 minutes are gone. after rebooting, another update and so on.
Windows has the worst update mechanism of all major players and it isn't getting any better in win 10.