Frozen MacBook Pro

My MacBookPro is two weeks old.

I was typing an email and the laptop froze. Couldn't type anything else and the beach ball appeared and has been going for half an hour.

I have start up screen and can use the mouse to wave the beachball around. I have the password window but can't enter a password and there is a Cancel circle but can't cancel.

I would normally power off and then power on but there is no power off button. Can anyone help please?