As a practising Christian I still manage to believe in a life after this one.
I do not know what form it takes, nor does anyone else. And the gospels do not record the risen Christ having described it, either. If you don't believe, you will probably see this as a confirmation that there is no life after death, and that the disciples either were hallucinating or lying. If you do believe, then you probably like me, feel that we obviously are not supposed to concern ourselves with the details of it - just accept the Lord's words "I am the Resurrection and the Life"
Down through the ages, various people, both saints and quite ordinary people have believed they had been vouchsafed visions of heaven, hell or pugatory. Whether these were genuine, wishful thinking or fantasies, I cannot pretend to say,
My knowlege of the Bible includes the warnings against trying to forsee the future, which has satisfactorily stopped me from ever wanting to consult a medium.
If there is a life after this one, then it is not unbelievable that ghosts, whatever they are, do exist. I grew up in a house that had a "presence" that could be called a ghost, and have as an adult lived in a flat that had a completely harmless little ghost - a black cat, seen by many others than myself, and I had not mentioned to any of them that I knew she was there.