My friend has a laptop that is stuck in Extended Desktop Mode when there is an external monitor attached. He cannot change it back to mirror displays. I had this same problem with my laptop and I and to do a system restore to get it working again. He's hoping to avoid this. Any suggestions?
try to plug in the screen open screen properties and select the dark coloured second monitor it should say something like not active right click it then click active the click this is my main monitor and the hit apply it should work unless you stuffed it up really bad if you need more help ill try to help you seya