What to do for flu in 2yr old?

Keep them cool if they have a temperature. (Loose clothing, not too many bedclothes etc... ) Use a child's paracetamol preparation to lower temperature quickly (such as Calpol). Keep them in bed until they're feeling better. Make sure they're drinking plenty of fluids. Vicks or Olbas preparations are good for clearing blocked noses (dissolve half a teaspoon in hot water and inhale the vapor, or just use the preparation topically), as are Halls lozenges or anything else that tastes really strong - I wouldn't really use a decongestive medication on a child.