Toshiba won't start?

I'm having some trouble with my windows 7 toshiba laptop. It's fairly new and I haven't downloaded anything really unusual(a couple mp3s, audacity, wlmm etc) I was using it and it just closed all my programs and shut down normally. This had happened once before but I thought nothing of it and it turned on fine afterwards. This time, when I turn it on, it shows the windows startup screen, then goes to a black screen, then the screen goes off. Then it turns on and repeats the same thing in a loop. The power light never goes off :/. I have left it like this for over 6 hours plugged in and it was still looping the same thing, so then I unplugged it and waited for it to die, hoping i'd get a system resume page, but when I turned it back on it just did the same thing. I have left it off for a week then tried again...Obviously that didn't work. There is no damage to the computer itself, I haven't dropped it or anything and it's not scratched. I'm no computer genius and I just don't know what to do. Help please?
So, thanks in advance for your help and for reading :)