What is everyone's remedy for a hangover? The timing of this post is probably spot on as it is Saturday morning for many here.
My perennial favorite:
1. McDonalds Egg McMuffin and a large coke. There is some magic ingredient(s) in their Coke without a doubt.

As already said, Berocca or some similar multivitamin will cure the vitamins depletion. You need to drink enough of liquid, better something that will help restore your sodium/potassium balance - mineral water, Gatorade or something better, since Gatorade is not really the best. You may eat banana or two, they are rich on potassium and will help you with glucose levels.
Simple Coca-Cola may also help if you do not have access to any of those.
If you have a headache - add plain Aspirin to all that.
Aside from above, you are often depressed and feel symptoms similar to withdrawal from stimulants, you may wish to use some of those to cure this. Caffeine or something from the same group. However, I do not recommend this unless you need to do something urgent, this is quite unhealthy.
Any similar multivitamin will do.