If you windows is reinstalled after Linux, and then grub is restored in the recent versions of grub one may come across the problem in windows booting:
BOOTMGR is missing
Press Ctrl+Alt+Del to restart
This is because, grub-restore will just recovers the earlier configuration file which contains the information about the UUID (Universally Unique IDentifier) of the earlier partition.
A simplest solution for this is to comment the line with -fs-uuid for windows partition.
To do this open terminal from Applications --> Accessories --> Terminal
Then type in:
gksudo gedit /boot/grub/grub.cfg
Find out the menu entry for windows ie;
the entry which starts with
#menuentry "Windows xxxxxxxx (loader) (on /dev/sdax)"{
With in that entry put a # symbol before the line
# search --no-floppy --fs-uuid --set xxxxxxxxxxxxxxxxx
Then save the file, close and restart the system to go into windows...
Cheers.........