My macbook pro is stuck on loading screen??

Hi I have a macbook pro retina 13" late 2013 and today i came back from school turned it on for a few minutes and had to leave so i turned it off. After a couple of hours i came back on and tried to turn it on but its stuck on the loading grey screen with the apple logo and the spinning wheel. I have os x 1.9.2. Ive had my macbook pro for about a month now. I tried to boot it in safe mode but it doesnt work. I dont know what else to do, by the way this macbook has no cd slot and i heard i can do something from my usb key or i probably misunderstood. Anyway someone please help me i need to use my latop now and i cannot and by the way i dont have any other laptops or computer and sorry for the spelling i'm on my phone and really angry anyway thank you !