One of my chirstian friends have question about ISLAM maybe this answer will help her to jogin ISLAM.she want to know that how she should believe that when we dead after that we will live again?

If she is Christian, this should already be one of her beliefs. The righteous are rewarded with the pleasures of what Christianity calls Heaven and what Islam calls Jannah. Does she say no, this will not happen?

How can your PROVE the UNPROVABLE?

If you can not live happily now how can you live another life happy.
The one is not for you.

If she is a Christian ( most faiths) she will believe she will live again, but she will believe that you as a Muslim will not live again, Most Christians believe that Muslims will not live again