Other than relying on religious texts written long after his supposed death, can you point out any evidence he existed? Any physical evidence found that isn't linked to some conspiracy website? Anything recognized by any trusted archeological sources? Same with any other prophets for that matter.
Mohammed existed. He is the only "prophet" for which there is any evidence.
However he didn't actually do anything special. No miracles at all. That is why the Jews declined to recognise his status as a prophet, prompting him to start his own religion.
He just ranted on like a mad man. Read the Qu'ran and you will see he repeated things over and over. His behaviour was entirely consistent with someone experiencing epileptic seizures of the temporal lobes of the brain.