Linking my mac to a monitor but my backlight has gone The back light on my mac screen has failed and I have the correct cables/connections to link to a monitor. The signal is coming through fine as I can see my wall paper. All my icons and files are to the "left" of the monitor screen, off screen but there. I can not get into system preferences to make the necessary changes as it is off screen. 
Does anyone know how I might be able to get round this problem. Thanks. Scott
A keyboard shortcut used to be cmd-F1. You may also try fn-cmd-F1.

Check this thread. It is rather old but has had recent updates.