Without seeing the summons it is difficult to say for sure what your options are. This may be a suit filed in general sessions court and likely a suit on "sworn account". If so, you technically do not file an answer. You can however file a sworn denial if you dispute the obligation or amount. This will force the other side to prove the obligation and amount. You would then need to appear on the date contained in the summons and defend.
You should consider meeting with an attorney to review the summons and you options.
This answer does not constitute legal advice nor form an attorney client relationship. I am not your lawyer. If you have a legal issue in Tennessee you may contact me for a free consult.
Meet with local atty who does collection defense. Go to court and look up case, request copies of all documents that were filed, so you can show them to an atty. Do this immediately.
Sounds like a Civil Warrant in Debt filed against you by a debt purchaser in Metro Sessions Court. You do not need to file a formal answer, but you do need to retain a good consumer defense attorney. In most of these cases, a Motion to Dismiss is in order under the Tennessee Collection Services Act or at the very least, a Motion to Compel Arbitration.
I would need more information to see what else is called for - without more information you just appear in court to avoid default.
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Nashville, Tennessee 37221
I am not your attorney nor is any answer I may provide legal advice. You may contact me directly for legal advice only if you are a resident of Tennessee insofar as I only practice in Tennessee.