I was born a muslim. but i feel sometimes that i do ot believe that allah exists. other times?

Despite the smarta*s tone of the answer, there was truth in what the one person said about being atheist. Actually, the Abrahamic gods (YHVH, the christian god, and allah) are all pretty much the same as far as the questions you have asked. My personal vote is to go for agnostic. You cannot prove god exists (any god). You cannot prove god does not exist (any god). Accept that and live your life to leave the world a better place than you found it. That is all that is really required of anyone, no matter what their "faith" may be, the rest is just made up stories and rules. If you must have some sort of practice, try Buddhism, which has no gods at all, or Universal Unitarian, which has no dogma and accepts anyone that is a seeker.