It's always best to do these things with the help of an attorney so that you what your rights are. That said, if your fiance wants to get a divorce he will likely need to file provided his ex didn't divorce him in the State of Tennessee (you may want to look into this).
The best way to go about it would be to get in contact with the ex and either attempt to file a stipulated motion and order to reinstate the case, or to file a new stipulated petition and judgment. When you file a stipulated divorce (stipulated means the agreement of both parties) you can file the petition, judgment, and all accompanying documents at the same time. This cuts down the time necessary to complete the process to a few weeks rather than a number of months.
Hopefully this gives you a place to start. Based on what you stated in your question, if a divorce hasn't been granted in Tennessee and you can't get in contact with his ex, your fiance will likely need to file a new case and proceed from scratch in order to take a default judgment. I'm not sure if you are aware of this as a resource, but I included a link to the Oregon Family Form Bank at the bottom of this response. As always, it's best to get a lawyer to assist with this sort of thing, but if you ultimately decide to go it alone I wish you the best of luck.
Jeffrey K. Traylor
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