Trying to do an Ubuntu/Windows dual install but only Windows 7 pops up

Question

So I've been running Ubuntu without Windows. I got a Windows 7 live CD and tried to do a Windows 7/Ubuntu dual boot but I couldn't get the boot to load correctly so I decided to go back to just Ubuntu. However now I just have a Ubuntu install and it won't boot. I've tried boot-repair and it still won't boot.

What should I try next?

Answer 1

Depending on the cause of your problem, updating or reinstalling the GRUB bootloader may be sufficient to fix it. One way to attempt that is to follow these the steps below.

1. Determine your normal system partition:

   sudo fdisk -l
   

   Look for the / partition.

2. If the partition is /dev/sda2, mount the partition:

   sudo mount /dev/sda2 /mnt
   

   You may need to change /dev/sda2 to a different partition, depending on what you discovered in the first step.

3. Bind-mount some other necessary stuff:

   for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt$i"; done
   

4. chroot into your Ubuntu install:

   sudo chroot /mnt
   

5. Now you're running your install in root and not the live CD so you can run:

   update-grub
   

6. If you face errors, you might have to re-install GRUB

   grub-install /dev/sda
   update-grub
   

   Usually this is /dev/sda, but if your system is installed on a different physical disk (as revealed in the first step), you may need to change this accordingly to say /dev/sdb, /dev/sdc, etc.

7. Hopefully everything works. Run these commands to exit the chroot and reboot the system:

   exit
   sudo reboot
   

_{For other ways to repair GRUB and further explanation, see RecoveringUbuntuAfterInstallingWindows and Grub2/Installing → Fixing a Broken System.}