Hi there, sorry to hear your bird is not well. Listlessness could be so may things, so I'll need some more information. Things to look for include: Feather loss, eye/nose discharge, appetite, any swellings, condition of legs and consistency of droppings. Also please let me know about the cage, its furniture and what food you are giving.
In my experience birds hide their illnesses well, so we may be short on time to solve this. If you haven't the time to reply to this with the required details then I suggest you take him/her to the vet ASAP. In the meantime, make sure the bird is comfortable, and offer water with a dropper or syringe, and some normal food softened with some water if necessary.
Best of luck to you, Vet Andrew
Thanks for reply, but I couldn't wait so took the bird to avian specialist last night, (very long drive).
She is on antibiotics and baby food, we hoping she will recover