So it sounds like the laptop is running, just the display is the problem.
Try turning off the laptop, connect any external monitor, turn on the external monitor, and then turn on the laptop.
If you can see your screens on the external monitor, then the problem lies either in the attached display or the ribbon cable that connects it.
If you can't see anything, even on the external monitor, then it is the graphics card that is done for, and you will probably need to replace the motherboard.
Either way, if the laptop is still under warranty, then I would contact the manufacturer about them doing the repair/replacement, so you don't void the warranty by doing the work yourself.