Request a copy of the garnishment paperwork for your employer, you are entitled to receive the information. The paperwork will tell you the information regarding the open Court case. Once you get the information, you should seek an attorney in the originating jurisdiction.
This should be addressed to FL attorneys. Also, gather all documents evidencing the adoption of the child. If the child was adopted, it means that your parental rights were terminated. You obligation for child support ends when your parental rights are terminated.