Restoring default theme in Ubuntu MATE 17.10 Slick Greeter

Hello!

I’ve changed default theme with LightDM settings manager. When I opened settings manager I’ve seen that the selected default theme name which I don’t know its name was not installed and had red “!” mark beside it. After that I switched to another theme.

Now I want to get the default theme back. It looks like default ubuntu login screen.
How do I do that? That default theme cannot be seen in options to select it.

Thanks!

Solved it by removing lightDM and lightDM-gtk-greeter settings and reinstalled slick-greeter.