The only way I know of that the windows key can be disabled / enabled is via the registry, this can be done either by manually editing the registry or downloading a registry file - info on this is here
https://support.microsoft.com/en-gb/...rd-windows-key
It seems unlikely that you could have disabled it accidentally by this method so the only other thing I can think of is that the key itself is faulty and not making contact when pressed. You could test this if you have a USB keyboard from a desktop computer by plugging it into the laptop and seeing if the Windows key on that works.