A cold is a viral infection which means only time and your immune system will kill it. Almost everything you do to "treat" a cold is actually a treatment of a symptom, not of the cause.

One thing you can do is when you have a fever, don't treat it and keep your body warm, but not dangerously so. This causes your cellular reproduction to slow down, therefore also slowing down the reproduction of a virus.

Going to bed early is also good - adequate rest ensures your body is able to do it's best to destroy those punkass hijackers.

Vitamin C isn't gonna help you, though. While it is an important component of the immune system, megadosing on Vitamin C will actually decrease it's absorption rate and you'll pee it out. And if you really megadose on it you could get kidney stones which I understand to be totally crummy and no good.

Rest, fluids, warmth, and waiting, sister.