Restoring grub in MBR

There is a lot of stuff about this.

But of course none worked for me :-D.
So I decided to post a solution that worked ;-).

1. Boot with any live CD (I've done it with Knoppix 3.x and Ubuntu)
2. Prepare directory for mounting:
   $ sudo mkdir /mnt/ubuntu
3. Mount the root (/) partition of ubuntu e.g.:
   $ sudo mount /dev/hda5 /mnt/ubuntu
4. Mount proc and dev filesystems on mounted partition:
   $ mount -o bind /dev /mnt/ubuntu/dev
   $ mount -o bind /proc /mnt/ubuntu/proc
5. If /boot is on seperate partition mount it:
   $ sudo mount /dev/hda4 /mnt/ubuntu/boot
   
6. Chroot the mounted partition:
   $ chroot /mnt/ubuntu
7. Populate /etc/mtab:
   $ sudo cp /proc/mounts /etc/mtab
8. $ sudo grub-install /dev/hda
   
9. Exit the shell
10. Reboot

Hope that it'll help someone ;-)