Ubuntu – Wubi installed Ubuntu 12.04 is not booting suddenly and showing GRUB prompt instead


I installed Ubuntu 12.04 3 years back alongside windows7 using Wubi installer. It was working very well till now but today suddenly it has stopped working after showing some errors when shutting down.

What I have tried:

I have tried every possible solution prompted by various experts at various blogs or sites. like boot-repair-disc and all.

I have found one strange thing and i am assuming this is the problem.

When I installed Ubuntu on Windows-7 using wubi-installer 3years back at that time , due to its small size (30 GB maximum), I decided to expand the "root.disc" and I made a backup of that 30GB "rood.disc" and expanded "root.disc" to 120GB size.

today, to check whether the boot problem arises because of external factors or directly from the "root.disc", I have replaced my "root.disc" file with 3 year old "OLDroot.disc" file, and now the system boots normally and works perfectly.

I have concluded that problem somewhere in my "root.disc" and I have used "root.disc" explorer software "ext2explore-2.2.71" to detect the corrupt file in the defective "root.disc" file.

When I compare the content of both the files, "OLDroot.disc" (3 year old) and current "root.disc", I have found that the entire "boot" folder is missing within current "root.disc" while "boot" folder is present within "OLDrood.disc" file and this could be the possible reason for not working Ubuntu 12.02 and showing GRUB prompt instead.

Is there any way to copy something into "root.disc" file because using "ext2explore-2.2.71" it is possible to extract files from "root.disc" but pasting something into it is not possible and if i could able to copy the entire "boot" folder from "OLDroot.disc" file to current "root.disc" it could solve my problem, how can i do it..

Best Answer

If You have a 12.04 Live CD or bootable USB, Boot using that to Live Mode.

Then mount your 'root.disc' and 'oldroot.disc' files in two folders in Live users home folder. (I'm assuming your two files as root.disc and oldroot.disc, You'll use the exact name for them in the commands)

First make two folders

mkdir newroot oldroot

Then mount them accordingly

sudo mount -o loop root.disc ~/newroot 

sudo mount -o loop oldroot.disc ~/oldroot

Then copy all files from newroot's boot to oldroot's boot

sudo cp -r ~/newroot/boot ~/oldroot/ 

After copy is finished, unmount both of the files.

sudo umount ~/newroot
sudo umount ~/oldroot 

Exit from live session. Make necessary adjustment to use the oldroot.disc file such as renaming. After that start your Ubuntu with the hope it is fixed.

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