A Chatauqua Airlines flight from Asheville, NC, en route to LaGuardia, ran into a little predicament in Mid-November 2011 when the pilot leaves the cockpit to use the restroom & ends up getting stuck. A passenger who hears the pilot banging on the door attempts to help the pilot. The pilot gives the passenger the “password” for the First Officer to open the door (which he wisely refuses to do).
From what I can find fighter jets were alerted but did not take off to intercept the airplane. There was no sign of intervention by an Air Marshal either. Commercial airliners are not supposed to land the plane without at least two people in the cockpit but I’m sure if there was a fuel issue they would have declared an emergency and attempted to land the plane.
Like I tell my kids, you should have gone before we left!