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A few days ago I was installing some software and power went down. When I rebooted, the partition to which the software was installed was not accessible. Disk manager shows that it's there, but doesn't show type, if it's healthy and gives me an error when trying to read its properties.

This is how it looks

The problem seems to be common after power loss, people recommend solving it by assigning a letter to the partition via DiskPart utility, but partition isn't listed in my case.

I can access that partition with bootable OSs (like bootable Ubuntu or winXP) and all the files are there, but another installation of Windows 7 gives me the same results as the original.

I could just copy all data to another disk if there was enough space, but unfortunately the size of partition I'm having problems with is 1.1TB.

How do I regain access to the partition in my original Windows 7 installation without losing any data?

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Copy your critical files off of the drive using Ubuntu before you start trying to repair it, or pay the consequences. – Moab Sep 6 '12 at 15:03
Did you follow the advice in that error message? – Ansgar Wiechers Sep 6 '12 at 15:03
I've been rebooting all day after that happened trying everything but formatting. – user1306322 Sep 6 '12 at 15:08
up vote 1 down vote accepted

Run diskmgmt.msc and see if it shows the disk and/or partition. If either the partition doesn't show on the disk, or the filesystem of that partition isn't recognized, try to recover it with TestDisk.

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Analyzing and writing whatever was detected by TestDisk restored the invisible partition. I was worried it wouldn't work so I backed up all the files before doing this, but it turned out to be okay. – user1306322 Sep 27 '12 at 16:30

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