How to Restore Grub 2 As The Main Bootloader

By | May 5, 2010 |

grub2-bootloaderFor those who are having a dual (triple or quad) boot system in your computer, chances are, your bootloader might break when you update one OS to a newer version. If you are using Ubuntu (with the new Grub 2 bootloader) and you installed Windows. The Windows bootloader will erase your Grub 2 and you won’t be able to boot in your Ubuntu. As such, you will need to restore your bootloader to Grub 2.

Note: If you are still using the Grub legacy, check out this post to restore your Grub.

Requirement: Ubuntu (Karmic or Lucid) LiveCD (download it from Ubuntu.com)

Start your computer and boot into your Ubuntu LiveCD.

The first thing that we need to do is to mount your existing Ubuntu partition. If you already know your partition number (of the form sda1, sdb2 etc), you can easily mount using the following command:

sudo mount /dev/sda1 /mnt    #replace sda1 with your partition number

If however, you have completely no idea of your partition number, launch GParted (System -> Administration -> gParted). Locate your Ubuntu partition and record down the partition number.

grub2-gparted

If you are are using different partitions for the root and the home folder, make sure you record the root partition instead of the home.

Close the GParted. Open a terminal and type in the following command:

sudo mount /dev/sda1 /mnt    #replace sda1 with your root partition number

Next, all you need to do is to reinstall Grub 2 with the following command:

sudo grub-install --root-directory=/mnt/ /dev/sdX  
#replace the X in sdX with your partition alphabet

Reboot.

You should be able to boot into your Ubuntu now.

Run the following to update your Grub 2 to include the bootloader of Windows (or other OS).

sudo update-grub

You should be able to boot into your Ubuntu and Windows (or other OS) now.



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Damien Oh is the owner and chief editor of Make Tech Easier
  • mnc2fan

    Thanks a lot.. this was the only guide that worked for me!

  • Aj

    Thank you, This was soo useful!

  • jin

    “Next, all you need to do is to reinstall Grub 2 with the following command:
    sudo grub-install –root-directory=/mnt/ /dev/sdX
    #replace the X in sdX with your partition alphabet”

    What partition alphabet? Linux or Windows?
    and how do I know the partition alphabet of linux?

    • http://maketecheasier.com/ Damien Oh

      if you look at the screenshot above, you will see that the partitions are listed in the order sda1, sda2, sda3 etc. This represent different partition in the same hard disk. If you have several hard disks, it will show up sda, sdb, sdc etc. Depending on your configuration, you will have to replace the sdX with sda, sdb or sdc.

      If you follow the above step and boot into a live CD, you should be able to check the partition alphabet with Gparted.

  • Shashanksharma21

    Thanks for sharing the info.. it really helped me…..

  • http://www.filehookup.com Lloyd

    This was the best explaining that I could find on the web! ThX..you are da man!

  • http://profiles.google.com/neerajmot neeraj motwani

    thanks alot

  • http://profiles.google.com/neerajmot neeraj motwani

    thanks alot

  • Diosanto

    Useful and simple. Thank you a lot! Good job.

  • Paul

    I did learn something from here and used it ti restore my grub though I did use another article. 
    I must say this article is already good for me.
    So in the end I had my dual boot ubuntu and windows running smooth.
    I did an article to share my experience dual booting. 
    Hope it helps others who didn’t make to work using this article.

    Try http://www.paullabis.com/2011/10/recover-ubuntu-grub2-after-windows.html

    Hope this helps and thanks author. This article did thought me something. 

  • Chinthaka

    Thanx a lot. This is simply explained what to do. Saved me from whole lot of trouble.