Here is my story: 1. I plugged an external VGA monitor to my laptor (Dell Vostro 3550) and configured dual display using System Settings/Displays. Everything worked well 2. I unplugged the external monitor, switched off my laptop and left my office 3. Being at home, when I turn on my laptop I get a blank screen on my LCD display. Ctrl+Alt+F1...F7 doesn't work. I assume that my primary display is still set to the external monitor, but I don't have any external monitor at home. How can I switch back to LCD?