Joseph Smith, a 14 year-old boy, prayed to know which of all the churches was true. In answer to that prayer, God the Father and his son Jesus Christ appeared to the young boy and answered his prayer. They told him that the Gospel in it's fullness was going to be RESTORED to the earth again. They told him that he would be called as a prophet and help in this great work. Later he was led by an angel named Moroni to ancient scriptures written on golden plates. He was able to translate them by the gift and power of God. The priesthood was then restored to the prophet by the laying on of hands by Peter, James, and John, three of Christ's original apostles.
I know that this is true and that all of these things did indeed happen. So how can you come to know these things are true? How can one possibly believe a story so crazy as this?
I think it is important for one to first believe that God is a God of miracles. Many of us believe that in the past God was able to work many mighty miracles. We read about them all the time in the Bible: the parting of the red sea, the raising of the dead, the healing of the blind, the visitation of God in the burning bush to the prophet Moses. Many of us believe that God wrought miracles in the past, but it is hard to believe that he could do so now. "And now, my beloved brethren, if this be the case that these things are true which I have spoken unto you, and God will show unto you, with power and great glory at the last day, that they are true, and if they are true has the day of miracles ceased?" (mor. 7:35) We must each answer this question for ourselves.
When we firmly believe that God can indeed work miracles we can then come to know that God has indeed restored his gospel upon the earth. And the way we come to know is the same way Joseph Smith did. We must Pray, "And when ye shall receive these things, I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy Ghost ye may know the truth of all things." (Mor. 10:4-5)
I know that God is a God of miracles and that he appeared to the young boy Joseph Smith and called him to be a prophet. I know this because I have read and prayed about the Book of Mormon. I know that you too can come to know this is true by the same power.