To recover GRUB2 after installing Windows

Your GRUB will be lost after you install Windows. To recover grub: 1) Boot with Ubuntu live CD 2) open the Terminal.      run sudo fdisk -l to see where Linux is installed     Look for the root partition. Might be like /dev/sda1     3) run sudo mount /dev/sdaX /mnt where X is the number you have found. 4) run sudo grub-install --root-directory=/mnt /dev/sda to install grub.     Note that /dev/sda without a number postfix.     Reboot it. 5) After re-boot. Run sudo update-grub to update grub.     This will update GRUB menus to add Windows boot loader. 6) Re-boot again to check that Windows boot loader added in GRUB menus. Enjoy...