No such thing as a hangover cure, once the hangover has set in, in my experience.
The best thing to do is to stop it from developing in the first place. My tried and tested method for this is having two slices of toast (must be toast - not pasta, not pizza, not a kebab, not a penguin) and a cup of tea before you go to bed.
After that, I invariably wake up feeling fresh as a daisy. If I don't eat that, then I wake up feeling like death warmed up.