My 4 years daughter has a running nose and clogged chest, what must give her to cure it?

Rest, fluids: She has a cold. It won't hurt her in the long run. There is nothing that shortens a cold. Recent research shows that decongestants and medications to reduce fever actually might make things worse. Some honey in water will help if she has a sore throat. See a doctor if she has high fever or if symptoms last more than 2 weeks. Lots of hugging probably is the test thing.