Did you hatch it or buy it? I would give 2 drops of Poultry NutriDrench (shake well) and follow by dipping it’s beak into water to get it drinking. Then place it in a warm cup or wineglass padded with a washcloth or tissues to get it standing. Keep it warm in the brooder. Offer water and food often. You can mix a little chick feed with water to make a thin paste. If you cannot get the NutriDrench right away, make electrolytes by mixing a quart or liter of water, 1 tsp of sugar, 1/4 tsp of salt. B complex vitamins, or liquid baby vitamins with riboflavin would be good to help with leg health. Good luck. I had hatch 2 chicks once who never were able to stand, but fell backward and arched their backs. We tried for 2 days to help them, but had to put them down.