My Macbook pro won't boot up!

Hello,
I was brought a new macbook pro by the project I work on a few weeks ago.
It was working fine yesterday and I did not do anything unusual with in, just some basic word processing. I shut it down normally but when I went to turn it on today it wouldn't boot up. It just stays on the screen with the apple and the spinning circle thing.
Does anyone have any suggestions on what may be wrong and what I can do?? I'm not much of a techie so have no idea what to try!
Thanks for your help,

Did you do any updates or install any software ?

No to both of them

Return the machine to where you purchased it from and have them look at it. Since it's under warranty, let Apple sort it out rather than try to trouble shoot it yourself - especially since the machine is new.

Regards.