Frozen at grey start-up screen

I have a two year old Generatioon 5 macbook. It has worked perfectly until about two months ago, when it started slowing down and programs froze a lot. Today, every program I tried froze and crashed, and when I reset my laptop, I wasn't able to get past the startup screen. It loads until the grey apple shows, and then stops but I can move the mouse.

I have tried holding shift when resetting and holding Comm+R. I don't use Time Machine (which is really unfortunate right now) and verifying/repairing disk permissions does not work.

Please help me...

Thankyou!