Why is my parakeet paralyzed, not eating, and what can I do?

In older small birds, strokes can sometimes cause the use of legs and the inability to grip or perch properly. Other potential causes can include calcium deficiency (which if she isn't on a balanced diet may be possible), bacterial infections such as Aspergillosis, viral illnesses, toxins and even diseases contracted from wild birds if Snowy has had access to the outdoors or with wild birds. If you haven't seen an avian vet specialist, or had any blood work done, that may be your next best step in figuring out what is wrong. Changing Snowy's environment some, such as including flatter or platform-like perches may also help with mobility so that she can continue to have access to food and water.