Have the above os.cant seem to find the enable button from unknown sources.could it be missing or should all versions of kodi have it?
That option was introduced in Kodi 17 (Krypton). If you're on 16.x (Jarvis) or earlier, it won't be there. In Krypton, the precise location may also vary depending on your skin.
Given that your previous posts give a strong indication of what you're trying to do, just remember you're on your own in terms of risk and what such addons may do to your system. That's why this option was introduced.
In Krypton it should be in Settings -> System -> Addons