We've all been there before, a day, a night, maybe even a week of feasting and letting ourselves go silly. I, for one, went completely nuts over my birthday weekend. Did the scale tip in an unpleasant direction the next Monday? Yes. What did I do about it? Not a whole lot.
Some people scold themselves for over-eating and then make lofty plans to Diet (4-letter word!) the next day or week. Food is not meant to make you feel guilty. We all over-do it sometimes, that's Life. What I recommend doing, instead hating yourself, is saying "That's ok! Everyone does it now and then. It's going to take a few days to get back on track. But those days will come and go in no time!"
Instead of dieting, stay on track with your normal eating patterns, but make healthier substitutions for an allotted 1-3, maybe 5 day period (depending on the "damage"). I always have oatmeal, no matter what, but instead of a turkey sandwich for lunch, I might have a salad. Instead of a full dinner entree, I might have steamed veggies and soup. Instead of a cupcake, I might have a lollipop. With some substitutions and your normal work-out routine, you'll be back on track before you know it. The key is Discipline, not Dieting.