What to do? We have a nest of baby robins in our back yard. Both robins are attentive to the nest, but I thin?

k one baby has fallen from the nest. The bird only has a few down feathers on head and down middle of back, tiny wings with tiny feathers. It is breathing rather heavily on ground, mother and father robin have both tended to baby, bringing food and sitting on/with. What to do? Do we place baby back into nest. One of the adult birds flew to chair on patio where we had been sitting as though to ask for our help. I've always thought never to pickup and move baby as parents will abandon, but I feel I need do something. What do you suggest?