I believe the number was 400 texts of religious gospels and only those of Matthew Mark Luke and JOhn were selected, becaause they fell into the desire of the Church. The accounts describes mostly biographical material, and not religious doctrine about the holy life, as they should have done. Jesus'(may peace be upon him) advice was not followed. The New Testament was not recorded during Jesus' lifetime but subsequently by later students. We know Jesus brough a Bible as previous Messengers revealed Divine Laws. But where is that Gospel? Both Muslims and Christians do not have any such manuscript. Perhaps buried, concealed, or it was destroyed and broken in war or unsettled times. It was at least a hundred years after the birth of Jesus before the Gospels were written down.
There is so much evidence that the gospel we have now is the same as the gospel before Muhammed's time. Yet, Muhammed told Christians during his time to obey the gospel and the Torah (the same scriptures we have today). If the scriptures are corrupt as you imply, then Muhammed is not a prophet seeing that he told us to search and obey corrupted scriptures. You can't have it both ways my friend.