Most cold viruses last from 7 to 14 days depending on the strain of the cold virus you have.
Most times when I come down with a cold virus I am feeling better after 7 days but in some cases the cold virus is more severe and last 14 days before it goes away.
There's not much a doctor or the hospital can do about a regular cold virus since theirs no cure for the common cold.
But if the cold virus lasts longer than 14 days or seems to get worse or you have trouble breathing or have other complications then a visit to the hospital or your doctor would be a good idea.
But if not then all you can really do is stay hydrated, get plenty of rest, increase your Vitamin C intake and wait it out.
Then after a week or two weeks you should feel better and the cold should be gone.
Also stay home from school or work until the cold virus has gone away and you feel better.