REINSTALLING GRUB

>> boot from the linux's LIVE cd without making any changes to your system and any of your partitions.

>> open up the terminal AND TYPE COMMAND
sudo fdisk -l

and check the linux system in it
if linux is there then type next command

$ sudo grub
-find /boot/grub/stage1
(hdx,y)

- root (hdx,y)
- setup (hdx)
- quit
- exit

thats all you need to and you will get you linux back and your window will be there too....