I recently installed Windows 7 on my laptop which already had ubuntu remix installed in it.
The problem i faced was, the GRUB was lost. But i had trouble getting your GRUB boot loader since the process of restoring GRUB has changed.
Follow these instructions to restore your GRUB.
1. Boot from your UBUNTU LIVE from which you installed Ubuntu
2. Now open up the terminal.
3. Now find out the drive in which you installed Ubuntu.
print the “Partition table” and find out the drive.
$ sudo fdisk -l
4. Now mount the drive.
$ sudo mount /dev/sdDP /mnt
‘D‘ is the drive number and ‘P‘ is the partition number.
In my case, It was ‘sudo mount /dev/sda3 /mnt’
5. Now install GRUB.
$ sudo grub-install --root-directory=/mnt /dev/sdD
‘D‘ is your drive. For me it was ‘sda’.
6. Now unmount the drive and reboot.
$ sudo umount /mnt
You should have your GRUB restored by now.