What Happens to your soul if you commit suicide.
In general, what happens to your soul after you die does not depend on how you died, by suicide, disease, or other means. It may affect the ultimate destination, however.
I will not go into whether the soul and the spirit are the same thing, or significantly the same. In my answer I will take your question at face value as asking what becomes of the eternal essence of man after death.
There are those that believe that the souls of unsaved persons will lose existence after death. That is, once one is dead, there is nothing else unless he is saved and going to heaven (or live on the earth in some doctrines). This is based on Matthew 10:28: "And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell." There are a couple of problems with interpreting this passage so that "destroy" means "annihilate." First, if these souls are to be totally annihilated, why does God need to do it in hell? Why not just end it when life ends? Second, if the wicked cease to exist after death, and do not face any punishment for things done in this life, where is the value in obeying God? If you obey, your soul lives on forever in God's presence, but if you don't obey there is no punishment other than missing out on any good there will be in heaven. This is like not receiving an invitation to a White House dinner. If you received one, that would be great. But if you don't receive one, you really don't suffer.
There is sufficient scriptural evidence for a final judgment (John 16:8; Hebrews 6:2 and 9:27; Revelation 20). Matthew 25:46 indicates that those judged guilty will be subject to "everlasting punishment." So the ultimate end of the soul is eternal reward or punishment. What happens to the soul between death and the judgment has been long debated, but has no bearing on the question.
Now to your specific question. What happens to the soul of one who commits suicide? The question could be rephrased to ask, "is suicide a sin?" That is, what happens to the soul ultimately is a result of sin or of having one's sins paid for by Jesus.
Murder is a sin. Taking the life of a person is against the laws of man and of God. This precedes the Ten Commandments, and goes back to the murder of Abel in Genesis 3. Suicide is murder; the only difference is that the victim is oneself. Even a murderer can be saved, if he repents. However, one who kills himself can not repent of the sin. He can not have repented ahead of the act, because carrying through on the suicide proves the repentance was not genuine. So, the answer to your question is, the soul of one who commits suicide will probably receive eternal punishment. However, there is no direct scripture that says that.
On the other hand, the blood of Christ continually cleanses those that have been immersed for forgiveness of sins (1 John 1:7). Therefore, if one belongs to Christ there is the possibility that he will be forgiven even if he cannot repent of the sin.