Grub Rescue on Ubuntu 12.04

OS: Ubuntu 12.04

I have two versions of Ubuntu installed on a low-end PC. I resized partitions and it finally messed up the grub settings and I finally ended up getting a grub rescue > prompt on reboot:


I could finally resolve it but still I am not sure if it is the right method. If you know a better method, please let me know.  I basically followed the instructions given here.


Step 1.  It is necessary to identify and locate the partitions where the boot images of your distribution is available.

grub rescue> ls
(hd0)  (hd0,msdos3) (hd0,msdos7)  (hd0, msdos2) (hd0,msdos1)

grub rescue> ls (hd0,msdos1)/boot
... grub .. initrd.img-3.2.0-43-generic-pae ... vmlinuz-3.2.0-43-generic-pae ...

This is the right partition where we would like the grub to boot into

Step 2. It is necessary to find "linux.mod" file which usually lies inside /boot/grub folder.  Do the following:

grub rescue> set prefix=(hd0,msdos1)/boot/grub
grub rescue> insmod (hd0,msdos1)/boot/grub/linux.mod
grub rescue> insmod part_msdos
grub rescue> insmod ext2
grub rescue> insmod gzio

Last two may or may not be necessary. At least I don't get any errors so far.

Step 3. Now its time to tell grub to find the boot images.

grub rescue> set root=(hd0,msdos1)
grub rescue> linux /boot/vmlinuz-3.2.0-43-generic-pae root=/dev/sda1 ro 
grub rescue> initrd /boot/initrd.img-3.2.0-43-generic-pae
no partition found 
grub rescue> boot

The initrd command does not work for me. However, the system boots properly and I get back the login page of my distribution.

Once I log into the system, I open a terminal and install the 'boot-repair' package as follows:

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

I go for the 'recommended step' and everything gets into its place. When I reboot, I get 

the usual grub menu. If you have a live CD or Live USB, then you can boot into the system 

and install & run boot-repair as explained above to restore your grub.