When you hook up a laptop to an external monitor you have to press a few buttons in order to change the output from the internal monitor screen to an external monitor. To do this start u your laptop, and press and hold the function key which is the letters "fn" inside a box. Press and hold this with the corresponding F# key that has the monitor symbol, which may look like this " lOl " or some variation of that. This happened to my brother's old laptop, he broke the screen and I just hooked it up to an external monitor and it worked fine. It m ay not kick on right away with mine, what mine does is it starts up on the external screen then dispears when you log onto the computer, so what I do is I log on, I just type my password because once the log on screen kicks on it automatically puts the cursor in the password box, so I put in my password and I press the function key; "fn" and I press and hold it with F4 which is my external monitor key, then after a few seconds my external monitor kicks back on. Hope this helps!!