It may be the graphics card/GPU or it may be something else.
First try this..
1. Turn off the laptop.
2. Connect an external monitor.
3. Turn on the external monitor.
4. Turn on the laptop.
Can you see your screens on the external monitor?
If yes, then your problem is probably either the ribbon cable that connects the attached display or the display itself.
If you can't see anything on the external monitor either, then it is probably the graphics card/GPU, which may well mean the motherboard needs replacing as well.
Check your warranty. If the laptop is still covered, contact the manufacturer about a repair/replacement. If not, well you are free to do the work yourself, or get a local tech to do it.