You need to hire an attorney to file both a motion to enforce and potentially to modify.It is unlikely the court is going to go to supervised visits this time, but you may be laying the groundwork for that in the future. It all depends on the evidence and the judge.
If you do not have your son back you can file a writ and get an immediate court order where the police will retrieve your son. If he's back you can file a motion to enforce and request make up time. If he's abusive you can seek a restraining order and or modify your current orders. Talk to an attorney about your options. Strategy depends on specific circumstances.