‘Despite being the custodial parent, I allowed my 12 year old son to go live with his father because my son said he wanted to. Now his father will only let me see my son when he chooses and only in his presence. How do I get my son back since his father is saying he won’t let me have him. When we made the arrangement, his father was in agreement that it was only temporary.’
If it has only been a short while, and if you have a court order that spells out specifically when your son should be with you, then if your ex will not let you have your son during the times ordered by the court, your ex is guilty of parental kidnapping, and the police will (or should) enforce your court order, meaning they should accompany you to your ex’s house and help you retrieve your son.
If, however, your orders from the court do not spell out that your son should be with you during specific times, or if you have let the situation go on for a while, you may need to file a motion with the court to have your orders clarified, and your son returned to you.