The knowledge does not get lost through the centuries, it is present, it is taught and it functions nowadays for the ones who try to practice it. Knowledge is like the light: if you turn on the switch in a room that has been in darkness for five hundred years, how long it will take for the darkness to disappear? It happens in an instant. It is not happening through a process of thinking. It happens through seeing, listening.
In Sufism knowledge is timeless. When you want the light to reach you, it happens to you instantly.
The method is important but more important is your relationship with the Shaykh, to be ready to accept his guidance, his rescue service. Because the ego is a clever self defense system and will integrate in itself even meditation and prayer. Millions of people on Earth pray and meditate and where are the results?
The first ‘work’ then is to find a guide for you. This is the most precious thing.