The best news I have had regarding this condition is that a percentage of people will recover their sense of smell, especially if it is caused by a virus. It is important to start Smell Training as soon as possible, as this will help the body-brain connection and exercise your brain to be attuned to scent.
Don't give up seeking answers! Doctors don't know everything about this condition yet, particularly because it involved the brain, which is a new frontier for science and research.