I was trying to hook up a new NEC 27 inch high resolution monitor to my laptop. After getting everything hooked up (power cable, HDMI cable) and powered up, my laptop screen went sideways and the NEC external monitor came on for brief moment, then went dark. The function keys work on the NEC monitor, but that's about it. After that, I shut down my laptop and rebooted. After rebooting, my laptop screen is dark and won't come back. I guess it's trying to recognize the other monitor. How do I get my laptop screen to come back?