how to enable registry disabled by administrator

Open the Notepad

and copy the bellow code and paste into the notepad.

 Windows Registry Editor Version 5.00
    [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
    "DisableRegistryTools"=dword:00000000

now save it as "anything.reg" and dont forget to to select file type as all files while saving otherwise you will not been able to execute it
now close the file and double click on file then press ok
then you can access the registry.