Oh this is such an unpleasant thing to have so you all have my sympathy.
The Epley manoeuvre is successful for a lot of people, in many cases followed up by eye and head moving exercises such as the Cawthorne Cooksey ones.
These have to be done two or three times a day for several weeks.
If the vertigo goes on and on though, up and down the country there are a few hospitals which have specialist balance clinics which have sophisticated diagnostic equipment in them which enable the consultant to discover just what is going on with the person. These clinics just deal with dizziness problems unlike normal ENT departments, so they are staffed with very experienced medics.
Unless we suffer from this it’s hard to describe just how horrible it feels, even though it’s quite common.
It’s reassuring to know though that there are specialists who can help if it goes on too long.