Drink water, and eat something light such as crackers, soup, bananas, or apples. This will help replace your loss of nutrients. Also take a pain reliever with your food for easy blood flow to your brain. Doing all of this together could make a drastic change with how you’re feeling. If it’s so bad that you can’t eat, the best thing to do is to drink some sports drinks, and get more rest. When I have a hangover, I’m usually in bed watching a movie relaxing all day.