This is not a miracle cure and it requires a some time and effort but it does work.
Step 1 - Don't languish in bed all day. Get up as soon as you can stand.
Step 2 - Prepare a fruit salad with the following ingredients:
half a papaya
half an apple
a thick slice of pineapple
juice of three oranges
Step 3 - Eat fruit salad accompanied by half a litre of green tea and as much water as you can manage.
Step 4 - Take a vitamin B complex or multi-vitamin tablet.
Step 5 - Go for a long walk, two hours minimum. This is the most important step and also the one requiring most self discipline.
Step 6 - Eat a good lunch rich in carbohydrates.
By afternoon you will have returned to you former self and your hangover will seem like a vauge memory from a bad dream. You may, if you wish, begin to plan the festivities for your next night out.