P.C Display issue

I have an HDPVR2 and I accidentally clicked the extend function on my display settings. Now every time I plug in my device my PC screen goes blank and my pass through to my t.v is blank as well. How can I change my display settings back when I can't even see the screen on my p.c?

Do I need to delete the device on my USB device list and set it up again? Or is there a key command I can type in to manually reset it.