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How can I repair grub? (How to get Ubuntu back after installing Windows?)

I am trying to dual boot Ubuntu 10.10 alongside Windows 7, after install I receive no Grub menu and I boot straight to Windows.

I can tell the partition took effect when looking at my C: drive. I was told there doesn't have to be a Grub menu and I can make Windows sub servant. Any help would be awesome!


Grub needs to be installed on primary boot partition. I fear in this case Grub is not installed on the primary partition which is active.

Edited on 4th feb: Procedure to install GRUB

I am assuming you installed Ubuntu FROM USB, but to a hard disk, not on USB.

Pre-requisites: Standard pre-caution -Have windows backed up in case anything goes wrong

Then, Boot from a live CD/USB and open terminal.

The issue the command sudo fdisk -l

This will list the partitions on every hard disk. On the boot colomn the partition with '*' marked is your default boot partition. If Linux partitions are detected, you will see the 'id' column with number 83 (Linux)and/or 82 (swap). Normal windows partitions will have ID 7 (HPFS/NTFS). There are more possible options, but these are major.

GRUB (now GRUB2) needs to installed on the default partition

Mount that partition to /mnt sudo mount /dev/sda1 /mnt (assuming your disk is sda primary boot partition is named as sda1, replace with your actual partition name)

Issue command to install grub2 on that partition.

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

This should install grub on correct location (Will look the boot partition and install it there).

Reboot, now you should see GRUB menu and should be able to dual boot to Ubuntu and Windows.

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  • How would I install Grub? I read I needs to be done from a LiveCD but I installed from a USB, does that act in the same way? – user10097 Feb 2 '11 at 16:14
  • Hi, I have almost the same problem as @user10097, only I installed Ubuntu 11.10. I tried this procedure but I get an error "Error: File not found grub rescue>", any idea what the problem could be? – Guille Nov 27 '11 at 23:13
  • @Jamess: as far as i know, GRUB2 can be installed on any partition, even not "boot" flagged, or on logical partition, so i am very surprised when you write "Grub needs to be installed on primary boot partition". Maybe i am wrong, so please could you give more details or sources ? thanks and merry Christmas :) – LovinBuntu Dec 26 '11 at 0:19

Nowadays we have Boot-repair which is pretty neat program with GUI and it should fix quite a lot grub problems. You can find it at: https://help.ubuntu.com/community/Boot-Repair

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Try this link: http://ubuntuguide.net/how-to-restore-grub-2-after-reinstalling-windows-xpvistawin7

just try to fresh install the Grub to your partition and see if you can find the grub menu again.

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The ubuntu wiki is here https://help.ubuntu.com/community/Grub2

If after reinstalling grub it still fails to show, we'll need more information. Easy way to get all the information is to run the bootinfo script.


Also are you sure you installed as a dualboot and not with wubi?

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I was anxiously waiting for the release of ubuntu 11.10 bec i bought a brand new acer aspire 4755G for the purpose of running a 64-bit os. Imagine my chagrin when it rebooted & wham, windows7 ?!? What an insult! This was quite a contrast from the 32-bit ver which i managed to install alongside before & the grub menu came up automatically!

I spent most of today pouring thru blogs, articles, even youtube videos til i an article, but it had to be read with many other articles & videos that i found. In other words, it was somewhat incomplete.

Here's what you need to do;

  1. boot from cd

  2. choose to try out ubuntu

  3. ask for terminal session

  4. run the following command. This is my test pc, so i have several more partitions than my 4755;

alvinh@ibmsda6:~$ sudo fdisk -l [sudo] password for alvinh:

Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xee2bee2b

Device Boot Start End Blocks Id System /dev/sda1 63 81920159 40960048+ 7 HPFS/NTFS/exFAT /dev/sda2 81931500 86991974 2530237+ 82 Linux swap / Solaris /dev/sda3 * 86992099 252027719
82517810+ 5 Extended /dev/sda4 252028928 293969919
20970496 83 Linux /dev/sda5 86992101 134849609
23928754+ 83 Linux /dev/sda6 212973768 252027719 19526976 83 Linux /dev/sda7 134850560 212973567 39061504 83 Linux

Partition table entries are not in disk order

  1. identify the partition that you wanna boot from. eg /dev/sda6

  2. follow the instructions in step 2; step 2 Using Ubuntu 9.10 livecd or higher http://ubuntuguide.net/how-to-restore-grub-2-after-reinstalling-windows-xpvistawin7

Don't bother with the rest of the stuff unless u r not using a CD!!!

Be careful what you type, i had to redo the procedure abt 3 times before i got it absolutely right!

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