Computer step by step
 Make your Pc better
Type gpedit.msc and press ok
In the Group Policy window please navigate to User Configuration -> Administrative Templates ->
System and open Prevent access to registry editing tools
The Default state is Not Configured and Registry Editort is Enable
To Enable regedit select Disable
To Disable regedit select Enable

To finish press ok button and close Group Policy window
Type cmd and press ok
Please select, right and copy a registry key from below, then right click on command prompt window
, select Paste and press Enter

To Disable Registry Editor:

REG add  HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 1 /f

To Enable Registry Editor:

REG add  HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f

To finish please close command prompt window
Gpedit:          

Warning Computers running Windows XP Home Edition cannot join corporate domains. For this reason,
features that require machine accounts within a domain, such as Group Policy, are not available in
Windows XP Home Edition.

For more information please continue to read the official Microsoft article
This method shows you how to Disable/Enable Registry Editor from Group Policy
Please perform the following steps:

Please go to Start and choose Run ...
CMD:          
This method shows you how to Disable/Enable Registry Editor from Command Prompt
Please perform the following steps:

Please go to Start and choose Run ...
Disable:          

When you try to open Registry Editor this message will be displayed:
Registry editing has been disable by your administrator.
Type C:\Windows and press ok
In the windows folder you can find regedit file
Path:          
This method shows you where Registry Editor is located in Windows using Windows Explorer
Please perform the following steps:

Please go to Start and choose Run ...
Description:  

The Registry contains information that Windows continually references during operation, such as profiles
for each user, the applications installed on the computer and the types of documents that each can
create, property sheet settings for folders and application icons, what hardware exists on the system,
and the ports that are being used.

For more information please continue to read the official Microsoft article
How to Disable/Enable Registry Editor
Windows Vista Windows 7 Windows Xp
   
   
   
   
   
Description Path Disable Gpedit Back CMD Description Path Disable Gpedit Up Back CMD Description Path Disable Gpedit Up Back CMD Description Path Disable Gpedit Up Back CMD Description Path Disable Gpedit Up Back CMD Up Back