According to Islam, why have all the other revelations to the thousands of former prophets disappeared?
Other revelations to the former prophets have disappeared or have become distorted because humans are imperfect & deliberately distort the truth if it does not suit their liking. That means, each revelation revealed in the past, would have (eventually) been distorted by evil people that did not like what was revealed & so each revelation that occured (one after the other) would have become distorted (though parts of the original revelations do remain and are respected by Muslims). The Koran itself would have been distorted in the same way but: since it is the final revelation, it must remain till the end of humanity (so that all time in existance has a message from God) & That will mean, God will not allow the book to distort (though the religion & some people’s beliefs may change/distort/weaken).
