Pro tip: If you decide to fuck with your system registry, know what you're doing. If you're going to have someone instruct you on what to do, make sure they know what they're talking about.
Also, if Windows 10 keeps shutting off Windows Defender; and you have no other antivirus/antispyware software [Note Malwarebytes does not count as Antivirus] all you have to do is change/add a registry key.
Do the following: Ctrl + R >> Type Regedit >> Enter >> go the this path: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender >> Edit the value "DisableAntiSpyware" or simply add it as a DWORD Value and set the value to "0".