I've been reading the Bible and it says in Matthew that Jesus had 4 brothers and it mentions he had sisters, but it doesn't give their names or how many. I was wondering if you knew what happened to his brothers and sisters and what the sister's names were?

Matthew 13:55-56 [55] Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas? [56] And his sisters, are they not all with us? Whence then hath this man all these things?
See All... states, "Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas? And his sisters, are they not all with us? Whence then hath this man all these things?"

As you pointed out, there are four named brothers and some unnamed and uncounted sisters, though the plural use of sisters shows that there must have at least two. The only brother we know anything significant about is James. He is called "the Lord's brother" in Galatians 1:19But other of the apostles saw I none, save James the Lord's brother.
See All.... Paul goes on to refer to this James as a pillar in the church of Jerusalem (Galatians 2:9And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision.
See All...). Certainly, he is the James who had great preeminence in the church of Jerusalem as mentioned in Acts 12:17But he, beckoning unto them with the hand to hold their peace, declared unto them how the Lord had brought him out of the prison. And he said, Go shew these things unto James, and to the brethren. And he departed, and went into another place.
See All...; 15:13
See All...; 21:18
See All.... There is a good possibility that he was the author of the book of James, but this is in dispute by Bible students.

Now if the James who wrote the book of James was the brother of Jesus, then the author of the book of Jude may be the "Judas" of Matthew 13:55Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas?
See All....  The human author of Jude introduced himself as the "brother of James" (Jude 1:1Jude, the servant of Jesus Christ, and brother of James, to them that are sanctified by God the Father, and preserved in Jesus Christ, and called:
See All...). Another brief reference to the brothers of Jesus is when His brethren are named as some of those in the upper room in Acts 1:14These all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with his brethren.
See All.... This is despite the fact that they did not believe in Christ during His earthly ministry (see John 7:5For neither did his brethren believe in him.
See All...). I know of no other references to the brothers or sisters of Christ after His death and resurrection.