Fixing a zapped Ubuntu Master Boot Record!

This can happen if you install Windows after Linux, or if you move partitions around with GParted. Sometimes the GRUB boot up panel is not there, sometimes you get ERROR 15 which means it can't find the root partition.

First boot up with Ubuntu CD as a Live session.
In Ubuntu Terminal
sudo grub
> find /boot/grub/stage1
this gave me two locations, (hd0,1) and (hd0,4). The 0,1 was the one I wanted reinstated. so next command is
> root (hd0,1)
> setup (hd0)
> quit