I have just bought my new 4K monitor. I connected it to my laptop and it is working beautifully. I put my laptop in stand-up for a while. Then, when I reopened it, I couldn't connect my screen anymore (it is working with another laptop than the monitor is working).

In the Settings > Display I see this screen:

I don't have 6 monitors. I tried to disconnect and connect the monitor again without success. Also, I tried to remove from the registry (as I read in this article) the following keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\

\Configuration 

\Connectivity

\ScaleFactors

and restart my laptop but nothing has changed. The monitor I want to connect is a Samsung LU32J590UQUXEN 32-Inch 4K Ultra HD 3840 x 2160 LED Monitor. My laptop has a NVidia GeForce GTX 960M.