Is it possible that Ram and Krishna (hindu gods) maybe one among the prophets that Allah sent..?

Anything is possible. Allah knows best. my personal opinion is that yes, it is possible. These religions are based on good behavior and right living. People have a way of revering what they see as good, so yes, it is possible that prophets were sent to give a message and then ended up being worshiped instead. Jesus(bbuh) is an example of how this can happen.