She may not like being up by herself. You can try giving her some warm scrambled egg and feeding her by hand along with giving her some ACV in her water to see if that will perk her up.
Most will eat yogurt on it's own but a few won't, and you can mix it with some layer feed to see if she'll eat that. Throw anything out that she doesn't eat after awhile so it doesn't spoil/mold and make her sick.
If you have some of the liquid Poly Vi Sol vitamins (w/out iron), you can try giving her 3 drops of that along her beak for a week and then dropping the dosage down for the next week until she's better. Sometimes when they get stressed, that will perk them back up.
Hope this helps!