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Today I first installed Windows 7, then I installed Ubuntu 10.04. I installed Ubuntu as side by side. Then i restarted the system two times and both times I was able to login to Ubuntu. Then I thought I should test whether Windows 7 is working or not, and I was able to login on Windows 7 also. However, this time when I restarted, it crashed, and nothing was displayed on screen. Then I used the Ubuntu Live CD and I think I made a mistake. I went to the terminal and wrote the command:

sudo grub

and then

sudo apt-get install grub.

Now the system is not booting from both windows and the Ubuntu CD. So now what should I do? Please reply asap.

thanks

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2 Answers

I could recover grub many times by following these instructions at: https://wiki.ubuntu.com/Grub2#Recover

First of all, you must start your system from a live cd. Then

"METHOD 3 - CHROOT

This method of installation uses the chroot command to gain access to the broken system's files. Once the chroot command is issued, the LiveCD treats the broken system's / as its own. Commands run in a chroot environment will affect the broken systems filesystems and not those of the LiveCD.

1) Boot to the LiveCD Desktop (Ubuntu 9.10 or later). Please note that the Live CD must be the same as the system you are fixing - either 32-bit or 64-bit (if not then the chroot will fail).

2) Open a terminal - Applications, Accessories, Terminal. 3) Determine your normal system partition - (the switch is a lowercase "L")

sudo fdisk -l

If you aren't sure, run

df -Th 
Look for the correct disk size and ext3 or ext4 format.

4) Mount your normal system partition:

Substitute the correct partition: sda1, sdb5, etc.

sudo mount /dev/sdXX /mnt  
# Example: sudo mount /dev/sda1 /mnt

5) Only if you have a separate boot partition: sdYY is the /boot partition designation (for example sdb3)

sudo mount /dev/sdYY /mnt/boot 

6) Mount the critical virtual filesystems:

sudo mount --bind /dev  /mnt/dev
sudo mount --bind /dev/pts  /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys  /mnt/sys 

7) Chroot into your normal system device:

sudo chroot /mnt 

8) If there is no /boot/grub/grub.cfg or it's not correct, create one using

update-grub 

9) Reinstall GRUB 2:

Substitute the correct device - sda, sdb, etc. Do not specify a partition number.

grub-install /dev/sdX 

10) Verify the install (use the correct device, for example sda. Do not specify a partition):

sudo grub-install --recheck /dev/sdX 
11) Exit chroot: CTRL-D on keyboard 12) Unmount virtual filesystems:

sudo umount /mnt/dev/pts
sudo umount /mnt/dev
sudo umount /mnt/proc
sudo umount /mnt/sys 

13) If you mounted a separate /boot partition:

sudo umount /mnt/boot 

14) Unmount the LiveCD's /usr directory:

sudo umount /mnt/usr 

15) Unmount last device:

sudo umount /mnt 

16) Reboot.

sudo reboot 
"

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If your computer can't boot from any cd, windows or linux, your problem is not Ubuntu related. Check your bios settings first. Next suspect your cdrom drive. You might try using another computer to make a bootable usb drive, then trying reinstalling grub.

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