What version of windows are you using?
Rik from RCE
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If you do a cold shutdown of a system with applications running that have files opened, it can scramble the hard drive. Try running the disc check utility. If it doesn't see the drive at all, then it probably scrambled the partition table / boot sector. It may be recoverable with the appropriate tools, but it may be that you will have to restore the boot sector, repartition the drive, and reformat it.
rubberman
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Have you tried what rubberman suggested?
Rik from RCE
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Does it show up in Manage? Right click on your My Computer, select Manage from the list. Then click Storage then Disk Management. See if it shows up there.
Rik from RCE
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The only thing left to try is to remove the hdd from it's external enclosure and fit it into your PC internally and try manage.
If that doesn't work then you will need to replace it!
Rik from RCE
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