Window positions (screen locations) are saved in the system Registry. When you pull up an earlier window, it is displayed in the previous position, as acquired from the Registry.

The Registry doesn't know you disconnected a monitor. There are two solutions:
1) Re-connect the monitor and move the windows back to the primary monitor.
2) Use RegEdit and delete the keys for the module where the windows display on the secondary monitor. (NOTE, this option is not for the faint of heart.)