Same thing with me - NVIDIA Support and nothing else helped, wasted 4 hours on reboots etc. - just read your comment, undocked and redocked the screen part and...there it is again! No idea how that works but it works!
Taking into cosideration, that I almost sent my laptop in, this is an inmportant solution. Also - if your NVIDIA or any other piece of hardware is gone, do check if it shows under "hidden devices" in the hardware manager. With me it was, it was giving the error code 45 (device detached) - this might be a clue it´s the issue with the screen attach/detach mechanics. Do it before going for software, firmware, widows updates etc.
I informed NVIDIA custommer support in my country today so they know next time to check for this.