Please help me out with this . 

I have a dual boot of windows 8 and ubuntu ,
Everytime I boot on to my Dell XPS laptop , it gets stuck on to a screen of automatic repair . 

I have important data on that disk . 

AK

Boot from Ubuntu, navigate to the data, back it up to another HD, re-install windows.  We need much more info.

When I boot from my ubuntu . The OS (windows ) is unable to mount . 

It says drive has gone to hibernation .

What information should I provide ? 

Hi,

You can first press shift+f8 when restarting, then choose last good known configuration.

If you have installation media of Windows 8, you can boot from installation Media and in Advanced menu, please choose command prompt and run these commands:

Run Check Disk from a Command Line to Check for and fix Disk Errors
http://technet.microsoft.com/en-us/magazine/ee872425.aspx

Rebuilt BCD:

bootrec /rebuildbcd

Then check the results.

Hi,

Just checking in to see if my last suggestions are helpful. Please let us know if you would like further assistance.

I have proposed it as answered, and since this issue can be caused by corrupted startup data or failure of checking disk, please feel free to try my suggestions.

Any difficulty you encounter during my suggestions, come back with your current status.