I have a stupid problem with my monitor. I was in screen resolution and changed some stuff. it said that it was possible to use a screen 1 and screen 2, but i only have one monitor connected, I pressed the screen 2. ´so my problem is that my pc is connected to a monitor that isn't there..there is no signal to my monitor from my pc.

Is there something I can press to switch the screen or do I have to connect it with a new screen to fix it?

I use windows 7 and have a alienware standard keyboard.

If you are running Windows, there should be a function key combination (look for the blue FN key, and a function key at the top of the keyboard that looks like a display) to switch between monitors. That should work. Another approach is if your system supports multiple monitors, you could plug the display into the other port.

Press this combination to change between multi-display options. You may need to change between display settings:

Windows key & P together

To transfer an open window from a different display use this combination:

Windows key & Shift & Right Arrow or Left Arrow depending on which side the open window is on.