SHL (sudden hearing loss) according to one ENT I spoke with is fairly common in young and middle age adults (20-60). No one knows for sure, but physicians assume it is due to a viral infection that permanently kills the cells that are necessary for healing. They usually give you an MRI if you present with this at an ER to rule out a tumor. I was affected at the low end of the spectrum at age 22; I have never recovered my hearing and I am 69 now.
When this first hit me, I had vertigo for several months, but slowly that dissipated.
Supposedly, there are hearing aids that can be fitted for this problem. In my 40s I was talked into dropping a lot of money on one. I disliked having molded plastic in my ear all day, and despite the outrageous expense stopped wearing it. It magnified all noise and was irritating to boot. It never helped me in my daily professional life back then. If you explore this option, think long and hard before falling for the audiologist’s sales pitch. BTW the audiologists now get PhDs, so they call themselves “doctors.” Just like the NPs; they get a doctorate in nurse practionership and call themselves “doctors.” It is an intention blurring of the boundaries. Physicians are very bad at guarding their turf. They are mostly humble people, and I find all the paraprofessionals I meet think they know A LOT more than they do. That puts patients at risk, but it is part of the breakdown of American medicine.