Boot off of the Windows installation media
Select Repair your computer,
Select the OS to mount for the recovery tools, this post demonstrates using Windows Server 2008 R2, but this should work for Windows Vista, Windows Server 2008, Windows 7, and Windows 8.
Open a command prompt,
Launch regedit and click on the hive to modify, then click file -> Load Hive,
Navigate to the \Windows\system32\config directory of the system partition for the installation to modify and open the correct hive,
DEFAULT -> HKEY_USERS
SAM -> HKEY_LOCAL_MACHINE\SAM
SECURITY -> HKEY_LOCAL_MACHINE\Security
SOFTWARE -> HKEY_LOCAL_MACHINE\Software
SYSTEM -> HKEY_LOCAL_MACHINE\System
The ntuser.dat file in the user's profile directory holds the registry data loaded under HKEY_USERS\<sid> (HKEY_CURRENT_USER for the logged on user).
Select a name that makes sense, I use something like HKEY_RESCUED_SYSTEM,
The hive is now loaded and can be viewed/modified as needed,
HKEY_RESCUED_SYSTEM holds the HKEY_LOCAL_SYSTEM\System hive for the Windows installation that we are trying to work with.
Windows Crash Dump Analysis
How to Perform an Offline System Integrity Verification
How To Rescue Files From a Damaged System