How do I get a divorce decree if I don't know where my ex filed?

If you don't know where your ex filed, then you were not given proper notice of the filing. If your ex filed properly, you would have received something in the mail. If he or she didn't know your addrress, it would be hard to get proper notice to you. He or she would have to show that he or she had a correct address and couldn't get you served and then he or she would be allowed to then publish the notice in a newspaper of general circulation where you would be. If you know where your ex lives or lived, check the court in that state. That is most likely where this person would have filed for divorce.