@AlainAlam: There are no answers really. The questions are purely constructs of religion, if religion tells a story that doesn't conform to reality, there will always be questions about it, a good answer would uncover more than it hides.
For me the answer is this: they're dead, done, their bodies get consumed and grow into plants and "all memory of them is forgotten".
The more scientific way of putting it: your entropy increases (at least it makes more sense to me in the mathematical/cosmological sense) and you are just a small part of information through space and time. Dying is just the maximal entropy your biology will allow.
The problem is that our brains are not naturally wired to understand cosmological time, we want everything to be consequential and entropy to be maintained, so it makes sense that people would come up with ideas that explain an order to things even after you die.
This philosophy of mine does have consequences of its own: theoretically you could rebuild the information again and structure it so that someone can be 'resurrected' in some form. In that way, the religious would be right, something about us does live on for eternity but not in the structure we are told.