Got served papers for a car that was reposed few years ago, Im not paying it since I gave it back, what should I do about the papers I got served?

While ignoring legal proceedings is something which is commonly done, no attorney is going to advise you to simply ignore legal proceedings because judgments in the State of Nevada remain valid for 6 years and can be renewed continually so that (in effect) the Judgment never goes away.  The better strategy is to deal with the situation and creditor head on, to explain that you relinquished the vehicle and to explain any legal basis why you believe that you should not be liable for the deficiency balance.