For future reference"
I always keep 2 things on hand. Guardian Angel, which is sort of emergency vitamins for birds (or you could use Pedialyte from the baby aisle in the grocery)
And... baby bird formula, which again you can get human baby cereal in the baby aisle at the grocery.
With a young or sick or injured bird, I try to administer a drop or two of the vitamins into the beak per hour. Even if they won't open the beak, you can dribble it at the side and see them take it in and swallow. This takes forever to do but it is worth it.
The cereal or bird food mix up watery and serve if they are able to eat. Sometimes they'll dip into a small bowl of it. Other times you can offer it in a spoon or by syringe, too much to write here, ask me if you need a how-to.