Blank screen

If you have a fn key and an outline of a monitor on another key, hold down the fn and then hit the other key, a couple times if need be. It should toggle between an external monitor and the laptop.

If that doesn't do it, try attaching an external monitor, re-booting and seeing if it comes up on the external. Then try toggling again.

If it doesn't work, it's probably time for repair.

I would try reseating the memory(located on the bottom) of the computer. Also check to see if any lights come on at all or fans as that can determine the nature of the problem. But yes this is a serious problem(most likely hardware related) and if your not comfortable with taking it apart I suggest taking it to a shop. Just make sure if they say they need to replace the part ask for the old part back.