Blue Screen after modifying Windows registry - Recovery

Description
You changed certain value on your Windows machine's registry (HKLM). After a restart, the machine cannot start properly again. Windows never reached the normal logon page.
You want to revert the changes back to previous condition.


Resolution
Use a CD/DVD/ISO to boot to the Recovery Environment. Follow the wizard until you can open the command prompt. At the command prompt, type regedit.
In the registry editor, highlight HKEY_LOCAL_MACHINE, and then go to File and select Load Hive. Select the file from other drives. It could be in E:\(or F:\)Windows\System32\Config, and will be called just SOFTWARE or SYSTEM. Type any name when the wizard prompt for the hive name.
Go to the registry location where you performed the last changes. Revert the value back to previous working condition.
To unload  the Hive, Highlight that hive name under HKEY_LOCAL_MACHINE, and go to File and select Unload Hive.
Restart the machine normally.