there's a difference between getting sick, and getting rid of your sickness.
to prevent from getting sick, obviously you need a strong immune system. the high quality vitamins i take have strengthened my immune system so much that i haven't gotten sick since i've started taking them. everyone around me is sick right now but i don't get sick. of course everyone knows vitamin C helps prevents sickness because of it's help with the immune system, but most vitamin C supplements don't work well enough. there are compliments to vitamin C that makes it absorb unlike those straight up vitamin C stuff that you just pee out.
to get rid of your cold, as everyone here has stated, LOTS of water!!!! LOTS OF SLEEP!!! EAT HEALTHY!!! (and of course my vitamins have helped me out as well since i get good balanced nutrients in my diet)