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I have just reinstalled Windows 7 in an attempt to improve my computer's performance. My hard drive is split up in two partitions, the first of which is reserved to the OS and applications while the second is used for data. When reinstalling, I have reformatted the first partition and installed Windows over it. I've then proceeded to install about 30 programs.

I then discovered that my data partition isn't available anymore. Here are the symptoms:

  • The drive appears in "my computer" with its proper name and filesystem (NTFS).
  • The drive's properties indicate that the drive uses zero of zero bytes.
  • Attempting to open the drive causes a dialog saying "D:\ is not available".
  • A chkdsk on the drive completes normally after having analyzed 178000 files worth a total of 58 gb (which makes sense) indicating no errors.
  • An administrator command prompt cannot set the drive as current.

What's going on and what is the best course of action?


I've burned and am now running an Ubuntu Live CD and I can see and access all my data! Now, do I have to backup everything, reformat and put my stuff back or can I do something to make the partition Windows-friendly again?

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up vote 3 down vote accepted

If I'm not mistaken, you have yourself quite a problem. It would seem that your data partition is encrypted with your old windows install's encryption key. Of course, since you reformatted your OS partition, this means that the encryption key has been lost.

I figure you must have enabled encryption on the partition using Window's own encryption system.

You can either brute-force the encryption (will take ages) or you might be lucky enough to be able to access the data using a Linux Live CD/DVD and mounting the drive. Although it shouldn't be possible, I was able to recover data theoretically encrypted by Windows Vista in this manner.

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I do not recall turning on some kind of encryption on that drive so I really hope you're wrong. Is there any way to determine if a drive is encrypted? For the Live CD, will any Linux distribution make the job? Ubuntu is pretty much all I know. – Trillian Dec 12 '10 at 13:45
The Live CD lets me see and access all data, so that discards the encryption theory, phew! Thanks for that suggestion. – Trillian Dec 12 '10 at 15:16

I would run a recovery CD and duplicate the data onto an external hard drive as a first step.

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As suggested by akseli, Boot from an Ubuntu live CD, see if you can see the data and copy it to another drive


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The Live CD approach worked! I can see all my data. Do you think I can fix the partition or do I have to back it up and reformat it? – Trillian Dec 12 '10 at 15:15
Back it up for sure, then attempt partition repair, or just format and copy the data back. – Moab Dec 12 '10 at 17:03

For some strange reason Windows 7 installation does so.

The solution is to add permissions manually. Choose your unavailable partition / Properties / Security / Edit. Most probably there is a group Administrators and no separate user account of yours.

Just press Add, type your User name, check all the available check boxes like „Read, Write” etc. OK, OK, Close and it should be available now.

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