The display on my MacBook Pro has recently died so I have been using the hdmi adapter to display the screen on my lg tv, which has been fine for a few day apart from the resolution not being ideal. Trying to fix this I un-ticked the Mirror Display option, making my tv a secondary display. Now I have no way of changing this back as all the options are on the primary display on my MacBook which has a dead screen! 

Is there any way to restore it back to the mirrored image. Or a way of using the secondary display as a primary? I'm really stuck here and would appreciate any help.