There are many causes of hearing problems. Ear infections can cause fluid in the ears that blocks sound. High fever from mumps or chicken pox can hurt the part of the brain that processes sounds. Loud noise can harm cells or nerves in the inner ear.
There is no cure, but some kinds of hearing loss get better. When fluid from ear infections goes away, hearing can improve. Damage from loud noise may not be permanent. There are also devices, like hearing aids and cochlear implants, that can improve hearing.