My Macbook Pro won't restart, internet stopped

Hi - My macbook 15" won't restart.

Earlier this morning I was on internet fine - then all of sudden I couldn't get on websites. I thought it was my wireless provider, but I got on this other computer and the internet is fine on it. So I decided to try and restart my computer, but it won't come back on! The apple on the top cover is lit, but the screen in black. It was recharged overnight, and is plugged in now, but that doesn't help. Does anyone have any idea of what I can do to start my computer up again, or know what may have happened with it getting on the internet?

Thank you for any help you can give me. Mac is exactly one year old, runs Mavericks. I have not (to my knowledge) upgraded to Yosemite.