Problem Scenario: When logging into Linux Mint, the first and only field for text is a password prompt. The corresponding username is not shown. You do not understand this. How do you get Linux Mint to prompt for a username?
Log in with the password of the user who just logged in. Go to Menu -> Administration -> Login Window. Uncheck "Automatically select the last logged in user." (When this setting is checked, the username is implied to be the most recent user who logged into the system.) Next time someone tries to log in, he/she will get a prompt to enter a username.