No user to login in MacOS High Sierra
Had the same problem and it is a simple fix.


restart your computer
when it "chimes" hold down "command" and "R" until a menu pops up.
Go to "Utilities" at the top of the page menu bar
Go to "terminal"
In the terminal type "resetpassword"
Follow the instructions. You may need you Apple ID. My Administrator account does not have an Apple ID, so I just reset the Administrator password without needing an Apple ID.


If you are not able to sign in with other accounts on your computer, go to your administrator account and make sure to uncheck Enable parental controls for those accounts in under System Preferences - Users and Groups. Then the other accounts should work fine.