Hi, Superbad55.
You could try using Safe Mode in Windows 8. It's a little technical, but there are step-by-step instructions at How-To Geek.com that cover booting into
Windows 8 Safe Mode. Once in Safe Mode, you should be able to reset your graphics settings to use the laptop as the main display rather than a monitor.
I'm a little curious as to how you were able to set the main desktop to an external display without one hooked up to it. Usually the option doesn't show up unless the system detects more than one monitor.
Anyway, hope this helps, and happy Simming.
Flynn