After disabling root user from the directory utility program, I returned to the main screen and all other user accounts were no longer showing on start-up as they were before enabling root user. Help. Please.

I enabled "root" user. It was an attempt (out of concern of granddaughter's age) to check on her history since I am the administrator. Realizing that this method was way more complicated than what I am capable of handling, I went back in to the Directory Utility Program and disabled the "root" user. I figured all was ok as I had not done anything while logged in as the "root" user. Instead, on restart of the computer, all users including myself were no longer showing on the startup. The only item showing was a blank place for user name and password. No picture. No guest. No users. How do I get those back and did I do something to cause this?