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I have installed Ubuntu as a dual boot with Windows 7 following the step on the installation. Ubuntu works fine, and Windows 7 appears as an option on the boot menu, but when selected, hangs. I was concerned to see files from my windows installation appearing in a Device called OS in the file manager. Have I lost everything? or is there some way back?

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How do you installed Ubuntu? Which version of Ubuntu do you have? Can you say which files are in the root folder of the OS device? Edit: in some cases, it can be solved using Boot-Repair. Using the Recommended repair option should solve anything related with GRUB fails. – espectalll May 1 '12 at 8:47
Thanks for replying. The version is 12.04 LTS. The OS device seems to have all the files and directories of my windows C:\ directory. – Mark Thomas May 1 '12 at 8:53
OK, it may be a problem of GRUB, the Ubuntu loader. Let me check... – espectalll May 1 '12 at 8:58
Check this: – espectalll May 1 '12 at 9:03
This only works if you installed it booting from the CD instead of Windows! – espectalll May 1 '12 at 9:04
up vote 1 down vote accepted

You just have messed up the MBR of windows. Just try to put a window DVD or USB(window setup on it) and start a system repair and fix the MBR of windows by the command at system repair:

c:\>bootrec /fixmbr

this command also worked for me to get back windows:

c:\>bootrec /fixboot

After that, you have to reinstall the grub loader. Just try a live CD of ubuntu and open terminal and write:

mount /dev/your_boot_partiton /boot
grub-install --root-directory /boot /dev/hda

Now You can dual boot both operating system properly. For me it worked well.
EDIT: You can view your windows partitions on linux as fdisk-l and listing out the ntfs partitions.
On windows, similar can be achieved by

diskpart>select disk 0
diskpart>list volume

and from there you can come up to know the partition of the window

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Thanks. I have a problem with the first part. The windows setup was on a hidden partition, and I wasn't given a CD. Can you tell me how to access the partitions? – Mark Thomas May 1 '12 at 11:58
Hidden? in which sense the partition is hidden? I mean from which operating system are you accessing the partitions? – ashutosh May 1 '12 at 12:56
From Windows - not sure of the details. I'm trying to get hold of a Windows DVD so I can follow your advice. – Mark Thomas May 1 '12 at 15:39
Drat - didn't work. I got hold of a Windows Recovery disc and followed your first 2 steps - both reporting success. The next step (on Ubuntu) had problems with /dev/hda. However I used Boot-Repair to fix grub instead ( and now have to entries for Windows 7 (on /dev/sda2 & /dev/sda3) neither of which work. Both hang after printing 8 dashes with a line of coloured dots along the top of the screen. Any additional help very welcome. – Mark Thomas May 2 '12 at 19:38

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