Repair windows

If you are able to see bootmgr missing in windows 7 8 or 10
Just follow following steps
1. Insert bootable media
2. Boot through the media
3. When install screen comes press shift +f10
4. Type diskpart and press enter
5. Type list volume
6. Chose drive letter in which windows is installed
7. Type exit
8. Type letter:(eg c:)
9. Type bootrec.exe /fixmbr
10. Type bootrec.exe/scanos
11. Type bootrec.exe/rebuildbcd

Vola just restart system and your windows is repaired.