I have connected an external monitor to my Dell N7520 notebook, than been playing with the setting a little on Control Panel\Appearance and Personalization\Display\Screen Resolution
I don't really know what i have done over there, but i accidentally have applied a setting that make the external monitor to show nothing, a black screen basically... trying to fix it, i accidentally applied an other setting that shut down my main laptopn monitor when i connect an external one :\?
to clear it all out, when i connect an external monitor, the main one show black screen and the external one is not functioning at all.. like its blocked?
how can i reset those settings to default?