Black screen and default monitor problem

Hello,
Hi how are you? I have an HP Pavilion laptop with Windows Vista on it. Over a month ago the monitor stopped working on my laptop. I connected my desktop monitor to it and it worked great. I assumed there was a hardware issue with broken wires or something. Last night I let the computer do it's usual vista update. When I turned the laptop on this morning, the laptop monitor was working again. I was shocked but very happy. I had to do some errands and closed down the laptop lid until I returned. When I got home. The laptop screen was lit up but all black. I had to plug the external monitor in again to see anything. I did some searching online and they said to try alt+F5 so I did and the laptop monitor went darker (unlit). The laptop is still seeing the external monitor as the primary monitor. How do I switch the primary monitor to my laptop, and how do I get my monitor screen to work again? Any help would be greatly appreciated. Thank you. :)