What can I do without hiring a lawyer to get my son back from my ex because she has been detaining him from me for almost 3 years.

There are not enough relevant facts to have a clue why (1) you've waited 3 years to make an issue of the matter; (2) your son's age, opinions, reactions, or best interest; (3) WHY your ex "freaks out" if you show up, etc., etc. You can get forms from the Clark County self-help center to file a motion to ask the court to alter the custody and visitation orders, but my guess is that the facts are sufficiently convoluted that you would have a far better chance of actually accomplishing anything with the assistance of qualified counsel.  Of course, that choice is years.  Meantime, for background, the relevant statutes, and other useful information, see: http://willicklawgroup.com/child-custody-and-visitation/