I have got Windows 7 and Ubuntu 10.04 LTS Lucid Lynx as dual boot, yesterday much awaited Ubuntu 10.10 Maverick Meerkat was launched so called the perfect 10, I was so excited to try my hands on it, I tried to upgrade through Internet as they have recommended on the site but my net connection is so slow that it was taking ages and I was getting impatient, then I downloaded the ISO image file and burnt on CD and try to upgrade it but it didn’t work.
Later I made up my mind that I’ll format the partition by login through Windows and install fresh Ubuntu installation, everything went smooth but when I restarted after installation it showed black screen with “Grub – Error: No such partition, Grub rescue” Damn, It gave me tough time to fix it I tired to reinstall Ubuntu three times but it didn’t work, later I followed following steps -
1. Booting from Live CD
2. Clicked “Try Ubuntu”
3. Go to Terminal or Crtl+Alt+T
4. sudo fdisk -l
You’ll get something like following screen

5. See where your Ubuntu installed, In my case it is on sda8, so that is the one you want to mount.
6 . Now on terminal type following to mount your right drive
sudo mount /dev/sda8 /mnt
sudo grub-install --root-directory=/mnt /dev/sda
7. Once you restart you’ll find your boot loader screen
8 Enjoy
