Dell Inspiron 5402

My laptop (Inspiron 5402) stopped working. it will not turn on when the power button is pressed and there is no noises, no lights turn on, and there is no other suggestion of powering on.But when i connet the data cable to Laptop , my mobile is charging.

When plugged in, the green light on the adapter turns on, but the light on the laptop itself that indicates when the computer is charging/on/etc does not light up. I tried holding the power button for 20 sec but no any sign occur.