|There could be any number of issues. Starting with the most obvious to least obvious:|
1. Are you sure the laptop is turned on?
2. Have you tried switching displays by pressing the Fn and F5 key?
3. If you attach an external monitor and switch to it with the Fn and F5 keys, does anything show up.
For number 1, the solution should be obvious.
For number 2, the problem should resolve itself by pressing the keys.
For number 3, your laptop will likely require service.