my laptop screen broken and is completely not useful, i have associate external monitor attached but its mirroring?

I would advocate replacing the screen. If you can twirl a screwdriver, it's not all that hard. Cost is usually $50-$100.
I've ordered from these guys: http://www.laptopscreen.com/ 4 times now, and been satisfied each time. Since ordering check to spawn sure they've directions for your particular laptop. I have found their instructions confident to tail.