Hang on to your hat.

OK, if this was mine I'd boot safe mode then head to control panel, device manager (this varies with window versions but you know where we are going so you have to get there.)

Now find displays and remove them. If there is an uninstall do that too.
Light reading:
http://www.bleedinedge.com/forum/showthread.php?23682-How-to-REALLY-show-hidden-devices-in-Device-Manager
https://support.microsoft.com/en-us/kb/315539 is for XP, but there are similar for other versions.

Finally I reboot and hopefully Windows on it's redection will get the parameters of the display right. If not I'm off to the display's web page to look for a monitor.inf or driver.