Even famous psychologists like Carl Jung believe in the existence of past lives. The mediums also believe in that but they have an other way to find some answers about this as about other issues.
How can we find some details about our past inside ourselves?
There are two main approach of this problem. One is outside, other is inside. Both of them have something in common, the fact that they both need the help of a professional except in rare cases.
As we said some psychologists believe in past life and their method to help people to find answers in themselves is hypnosis. It is simple, the patient as to be putted in an altered state of consciousness where he will be able to see his own past. According to professionals it is not dangerous and it can be done even by those who believe in god and are afraid by any religious sentence.
They use an other way to read our past: Spirits. The goal is to establish a link between live and dead people and to ask dead people on what the past of the customer was. This is clearly usually a bad way to get answers because the medium has to enter in contact with dead people who is not so simple and has to have a dialogue with someone who knows the one who wants to know about himself. So it is very hard to do.
If there is a life after death, why do we rebirth again? That’s a very interesting question. There is another one: If mediums enter in contact with dead people, how these dead people can be able to speak about us without knowing us? In that question, I think we have to dig in the side of the mediums who are mostly liars because they seems to answer also to questions even when they get no answers…