"Hard disk not found"

Source
System administrator rights needed to control the hard disks
No Drive Letters Show in Disk Management

Try rescan for drive information
Start/run/cmd
diskpart
rescan
When finished type "exit" to quit diskpart and "exit" again to quit command prompt window.
Recheck Disk management for missing partitions.

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If the problem is still valid here is a solution for you:
Start Windows - press Start - run - type regedit and press ok/enter.
Then find the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Class\{4D36E967-E325-11CE-BFC1-08002BE10318}
There you will need to select Edit - New - Multi-String Value.
Rename it to UpperFilters. Then right click on this value and select Modify. Type PartMgr.
Quit and then restart Windows.
Since then the drive letters will be in WDM. The cause of the problem is in rootkit viruses to my mind.