Why could cause me to stop hearing in my right ear?

Hearing loss: Temporary or reversible causes of hearing, wax in the ear, cold, eustachiantube dysfunction, fur uncle in the ear, osteoma in the ext canal, infections of the middle ear---or permanent loss can occur in otosclerosis, cochlear and auditory nerve defects, brain tumors- acoustic neuroma.

See your doc. : Could be as simple as waxy blockage, or more complicated things such as nerve damage. Your primary care doctor can do an initial evaluation and if needed, send you to an otolaryngologist.