Can someone please give me GOOD advice on breaking a diet plateau? 10 points for best answer!?

I have been on a diet for the past 3 months..i eat no refined carbs, nothing late at night, only water, and no sugar. I eat between 1200-1500 calories a day and I also workout between 2-4 hours a day. I have lost 33 lbs. However, the past two weeks i haven't lost anything! It's so frustrating! So I'm hoping that someone can give me some advice on how to break out of this plateau! thanks!