Ok. I'm not sure how much weight you'll need to lose, but I have a diet that I use when I need to lose weight quickly and it really works. You can lose up to 10 pounds in 3 days. Using it, I've lost 5 to 8 lbs whenever I've done it. You have to follow it completely and can't subsitute.
This may not be the healthiest option, but it is a diet created by doctors for cardiac patients who need to lose weight quickly before surgery. It is not something I would recommend for long term use for weight loss, but is perfect for the situation you're in.
It's called the "3 Day Diet". Here is the link. The meal plan is listed at the bottom of the web page. Good luck!