GPU not working?

Hi all.

So I'm having a very strange issue that I had once before, about 2 years ago. My nvidia GPU in my AW17 isn't showing up. It's running on the intel graphics right now. No idea why. When I look under display adapters in my device manager I only see the intel graphics, no nvidia GPU. So it's like not even registering that it's there. Not sure what's going on. This happened to me a while back, was incredibly frustrating. I was freaking out cause I needed the laptop for work, so I ordered another GPU and just as it arrived in the mail my current one popped up and started working again.
Anyone have any clues as to whats going on and how to make it appear again? Any help would be greatly appreciated.

 

Switch off the iGPU, check with GPU-Z/HWinfo if it shows up there

 

Fn+f5 to do what @Grant B Gibson said. Make sure your alienware overlays are installed but it may work without it i just dont remember.