I used to have a password prompt but then I, from somewhere in User Accounts, unchecked "Require a password for login." Now, I want Ubuntu to prompt for a password again at login screen, mainly because I have to manually unlock the login keyring whenever I access Dash or other services, which is a pain at best.
I also searched another question, namely How do I get Ubuntu to ask me for a password at login again?. It was of no help because the OP's question is "I have a password but Ubuntu doesn't ask for it."
Also, the two answers provided there don't solve my problem at all. They discuss completely other things.
Is there no simple mechanism? Because intuitively, if there's a checkbox option to bypass password requirement, there should be an equally hassle-free facility to again require the password.