Authentication to restart and turn off?
 

Recently I turned on autologin, but had to turn it off for privacy. Now, everytime I turn off, or reboot it asks for authentication because I have multiple users logged on. Any ideas? I can post whatever details you need.
(It hasnt felt normal lately anyways, sometimes normal things dont load right (The menu icon, volume, etc) It also may have to do with me uninstalling virtualbox, not deleting my hard drive. No idea, Im a bit tired to fix this, it may be really obvious.)

Before trying to shutdown, could you enter the command:
users

Do any other users show up besides yourself?

Does Linux mint use policy kit. I suspect that a policy may have been disabled when you made the autologin change (don't know why it should) and not re-granted when you changed it back.

To check if it does use policy-kit, enter this command as your regular user:
If some policies are shown but the four above aren't I think that granting these policies may fix the problem. First see if they are available:
To change the policies, use the "polkit-gnome-authentication" program.
It has a graphical interface and more importantly will save your changes.

Another area to look is in your configuration for users & groups, or for the power-save configuration.

Thanks the setting was off. I just went in the program and fixed, lots of help :)