Windows 10/Fix boot

Start from win 10 dvd and run in CMD:

Bootrec /fixmbr
Bootrec /fixboot
Bootrec /scanos
Bootrec /rebuildbcd

If "system device not found", run "diskpart"

sel disk 0
list vol
sel vol 3 (or whatver number the EFI partition is)
assign letter=z:
exit

cd /d z:\EFI\Microsoft\Boot\
bootrec /fixboot
ren BCD BCD.bak
bcdboot c:\Windows /l de-de /s z: /f ALL