I believe there IS life after death. Death is a depressingly inevitable consequence of life, but now scientists believe they may have found some light at the end of the tunnel. The largest ever medical study into near-death and out-of-body experiences has actually discovered that some awareness may continue even after the brain has shut down completely.
Death, As in Life, Is What We Make It. John Milton had it right--we make our own heaven or hell. There is an afterlife because there have been too many stories of near death experiences and ghost encounters. How can there not be life after death? My own personal view is that after we die, our spirit goes where it is most comfortable. If we were ready to pass on, we go to be with the Source. If not, we go somewhere else until we are ready for God.
There isn't an afterlife because after-life is death.
Death is inexperiencable because it's the end of life...even when you're dying you're still alive, but once you've died you're dead. I can't say much about near death experiences, except that those people were still alive. I don't know what ghosts are. I don't know about spirits. If by death you mean a physical death, then there's no physical life after.
I think because of continuity, and that rebirth/reincarnation is indistinguishable from just novel birth, it wouldn't be your life after your death, just another life. Sure, there's life after death; there will be people after you, but your life would be over. If it was continuous, it wasn't really death, just a transition, like moment to moment transitions in life (not the same person years ago, nor will be the same person years later).