I was watching tv and ran across somebody who said he was an apostle and prophet. How can we tell if a prophet is sent by God?
A prophet can be considered someone who speaks the will of God to the present generation. So, yes, there are still people who do that. The Holy Father and Bishops throughout the world preach a prophetic voice. And the laity are a prophetic witness to the world through the Christian manner they live their lives.
Jesus was at odds with the scribes and Pharisees about the way certain things were handled but Jesus always taught that they had legitimate teaching authority (Matthew 23:2). In the same manner, a legitimate prophet will not contradict the teachings of the Church. For example, St. Francis was highly critical of the way many clergy were living and treating the poor, yet St. Francis followed and preached the teachings/doctrines of the Church.