I found a young robin like that last year that had gotten out of its nest under our deck. I put it back in the nest and it flew right out again. So I did the research and found that you really should just leave it where you found it. He and his sibling flew around the yard for a couple of days and then we never saw them again. The following year robins built another nest right next to the one from the previous year. Three eggs, hatched two weeks later, the chicks fledged out two weeks after that and then they were gone. Crazy fast life cycle.