Problems when I turned it on!! :(

Hi everyone!!

I´m sooo freaking desperate!! I literally cried today about this whole macbook pro situation...
The thing is this... I was just using the internet and suddenly my mac froze!! I couldn´t even turned it off!! So, I had to wait till it ran out of battery power... I left it like that for a while, and then when I tried to turned it on again I could only see the screen turn gray and the apple logo came out... it started loading... and loading... and it could perfectly stay like that for hours...
Something like this happened to me like 2 weeks ago, but it was all back to normal when I decided to not use my mac for like 2 days straight... when I finally tested that it worked!! But, this time I have tried that and is not responding at all!!
Please help me!! I´m out of ideas and heart-broken...
Thank you so much!!

Ok, boot from your install disc and run disk utility form the file menu. This will show up any issues there may be with the OS, but, it could well be yet another Macbook Pro HD failure. If it's still in warranty, then back to Apple it will need to go.
How old is the MBP?

You could try archive and install, like above, your OS may have been corrupted. I had to fix a PC yesterday with the exact same problem. Repairing OS worked.