How to Repair GRUB 2 When Ubuntu Won't Boot

 

Using Terminal Method

If you have Ubuntu 12.04 installed, ensure you use a Ubuntu 12.04 live CD.

Open a terminal after booting into the live environment. Identify the partition Ubuntu is installed on using one of the following commands:

 

sudo fdisk -l

sudo blkid

 

Step 1

 

Here is the output of both commands. In the sudo fdisk -l command, the Ubuntu partition is identified by the word Linux in the System column. 

 

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Step 2

 

In the sudo blkid command, the partition is identified by its ext4 file system.

 

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Step 3

 

Run the following command to mount the Ubuntu partition at  /mnt, replacing /dev/sdX# with the device name of your Ubuntu partition from the above commands:

 

sudo mount /dev/sda9 /mnt

 

For example, use /dev/sda1 for the first partition of the first hard disk device.

 

Important: If you have a separate boot partition, skip the above command and mount the boot partition at /mnt/boot. If you don't know whether you have a separate boot partition, you probably don't.

 

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Step 4

 

Run the following command to reinstall grub from the live CD, replacing /dev/sdX with the device name of the hard disk above. Omit the number. For example, if you used /dev/sda9 above, use /dev/sda here.

 

sudo grub-install --boot-directory=/mnt/boot /dev/sda

 

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Step 5

 

Restart your computer and Ubuntu should boot properly.

 

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