I have a triple boot windows 7, ubuntu 10.10, ubuntu 11.10 and i want to delete the partitiion containing 11.10 but that's where my grub is located I believe. Because it updated to grub 1.99 when I downloaded installed 11.10. How can I change this so that even after the partition is deleted I can use grub.
Boot from a live cd like on of your ubuntu install cds and open a Terminal. Now mount one of your ubuntu partitions. Assuming /dev/sda7 is your ubuntu 11.10 partition you can accomplish this by issuing the following command as root user:
sudo -s mount /dev/sda7 /mnt
Now you can use chroot to change in the mounted operating system:
Now it should be easy to use grub-install:
Now change to /etc/grub.d/ where you should find a script called 30-os-prober. This script will scan the hard disks for other operating systems and add them to the boot menu. Therefor as root you should execute this script:
And as final step update your grub.
Also i found this helpful site.