This page documents how to restore or recover the boot-loader (GRUB) after installing Windows. Some reasons to repair your boot-loader might include installing Microsoft Windows after you have installed Ubuntu, adding or removing a hard drive, or changing hard drive settings.
Using the Ubuntu CD (Recommended)
The graphical way
- Insert your Ubuntu CD, reboot your computer and set it to boot from CD in the BIOS and boot into a live session. You can also use a LiveUSB if you have created one in the past.
Install and run Boot-Repair
- Click "Recommended Repair".
- Now reboot your system. The usual GRUB boot menu should appear. If it does not, hold Left Shift while booting. You will be able to choose between Ubuntu and Windows.
The terminal way
* Open a terminal. As of Ubuntu 11.10 and 11.04, this can be done by opening the Unity Dash (you can click the Ubuntu logo in the top panel or use the Windows key on your keyboard) and typing in "Terminal", and clicking what comes up. On earlier versions, you can achieve this by going to Applications -> Accessories -> Terminal. Alternately use the Keyboard Shortcut: CTRL + ALT + T.
For full details on using terminal to fix grub on hard drive from Live Installer DVD or Flash: https://help.ubuntu.com/community/Grub2/Installing#via_the_LiveCD_terminal
- You are then presented with a standard bash prompt, type - this only works to reinstall to MBR of a working system:
sudo grub-install /dev/XXX
where XXX is the device of your Ubuntu install. (eg: grub-install /dev/sdb). Hint: You can also use /dev/disk/by-label/ if the partition you installed on has a label. You can determine the /dev node for such a device by running:
ls -l /dev/disk/by-label/
This will give the output of something like:
lrwxrwxrwx 1 root root 10 Oct 16 10:27 data -> ../../sdb2 lrwxrwxrwx 1 root root 10 Oct 16 10:27 data2 -> ../../sda2 lrwxrwxrwx 1 root root 10 Oct 16 10:27 fat -> ../../sda6 lrwxrwxrwx 1 root root 10 Oct 16 10:27 home -> ../../sda7 lrwxrwxrwx 1 root root 10 Oct 16 10:27 root -> ../../sda1 lrwxrwxrwx 1 root root 10 Oct 16 10:27 swap -> ../../sda5 lrwxrwxrwx 1 root root 10 Oct 16 10:27 windows -> ../../sdb1
You can also use fdisk if you do not see the /dev/disk/by-label:
$ sudo fdisk -l Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0001bc54 Device Boot Start End Blocks Id System /dev/sda1 * 1 18725 150403072 83 Linux /dev/sda2 18725 19458 5884929 5 Extended /dev/sda5 18725 19458 5884928 82 Linux swap / Solaris
From here, find only the drive name, ignore the partition number, that is, for partitions labeled "root", "data2", "fat", "home" and "swap" it's all still just sda. This is due to the fact that GRUB is installed in the MBR of the drive, and not on a partition.
Trouble? If other things are messed up, e.g. if you have deleted the partition from where Grub was previously installed, grub-install may return an error message such as "cannot find a device for /... (is /dev mounted?)". You may have to do grub-install a bit differently. Refer to the handy guide on fixing a broken system
Now reboot your system. The usual GRUB boot menu should appear. If it does not, hold Left Shift while booting. You will be able to choose between Ubuntu and Windows.
Using the Ubuntu Alternate CD
- Boot your system from the Ubuntu Alternate CD.
When the Ubuntu splash screen comes up with the boot: prompt, type in rescue and press enter.
- Choose your language, location (country) and then keyboard layout as if you were doing a fresh install.
- Enter a host name, or leave it with the default (Ubuntu).
At this stage you are presented with a screen where you can select which partition is your root partition (there is a list of the partitions on your hard drive, so you are required to know which partition number Ubuntu is on). This will be dev/discs/discY/partX, where the X is a partition number and Y is the number of the drive.
- Now proceed as described in "The terminal way" above.