Solved! Blackscreen because of Nvidia control Panel?

[Schappi]

HI!
I need help guys my Laptop and Monitor were both working well until I decided to change the resolution (in my Nvidia control panel). Now just my laptop is working until I connect it with the Monitor then it and the Monitor will both just show a black screen.
Because I am on a laptop I can't access the part where I can reset the resolution without the monitor.
I hope anyone can help me:

 

[rgd1101]

unplug the monitor

 

[mrmike16]

I'm not understanding why you can't change the resolution back? If both screens are black, use Windows Key + P to change the display to your laptop only.