Macbook Air not turning on!

MY Macbook Air is not turning on for 3days now. The cable also don't show any light when I plugged it on. I only bought it last week. Please help me on this. It just won't turn on for no reason the night I last used it I shut it down properly and it's 90% charged and the next morning I opened it, it's not turning on when I press the power button and it's not evern charging.