How can I reset my display settings through terminal?

Removing ~/.config/monitors.xml should do it:

• Open a terminal window by pressing Ctrl+Alt+T
• type rm ~/.config/monitors.xml and press Enter
• immediately log out and back in. It should be reverted now

Alternatively

If you know what resolution your screen supports (e.g. 1440x900), you can run the command:

xrandr -s 1440x900

to at least temporarily set a workable solution, then subsequently change settings from GUI.

I had a similar problem to you but I found the solution here How to scale title bars and menu in Ubuntu 14.04 with the terminal only

dconf reset /com/ubuntu/user-interface/scale-factor

This changes the "scale for menu and title bars" to default.