Then just give it a quiet place to rest, with some food and water...maybe throw a towel over the box so it feels safe, and let it be for a bit. It might be in shock. Or, it might have been hit and be hurt but not have broken bones??? Is your house warm? maybe give it a hot water bottle wrapped in a wash cloth or hand towel.I have no idea to any of these questions other than I believe it is not injured.
(you can make your own 'hot water bottle' by taking an empty soda bottle (individual size) or a Gatorade/Powerade bottle. Fill it to all but 1/2 cup full, squeeze bottle some, and cap tightly. Then put in microwave until very warm. Warm enough so feels hot to hand, but can hold it for a min. or two before it becomes uncomfortable. Wrap in a washcloth or pillow case or hand towel, and tuck it in near the bird. (but not between it and food/water, don't want to make it hard for the bird to eat/drink.)