My second monitor is not being detected/not working

Ok, well, you need to 'enable' the secondary monitor via display properties, or Nvidia Control panel, it won't turn on by itself. Now, in the Nvidia control panel, it may not show the secondary monitor as 'being there to be turned on', and if that is the case, then the physical connection between the display,and the video card isn't working. Maybe the adapter, maybe the cable, hard to say. I hope this helps!