HowTo reinstall – restore GRUB in UBUNTU

After a windows fresh install, the windows setup decided to drop MBR to put its stuff in. 
This is an old trick, but udev added a little complexity, so let’s give it a try. First boot on a Ubuntu CD, open a console and run:
(here linux partition is sda2, second partition on a sata disk)
mkdir /media/mnt mount /dev/sda2 /media/mnt/ mount -o bind /dev/ /media/mnt/dev chroot /media/mnt => now you are on the destination disk, so you can install grub. grub-install /dev/sda
Of course you can do a lot more stuff, like changing fstab etc etc .. but the trick is to mount + mount bind + chroot