What do I do if relative received court papers demanding me to go to court for past due rent but I am currently out of the state

It is possible a default judgment will be entered so I suggest you rearrange your schedule and not let a judgement like a default be taken. It can lead to wage garnishment and collection against you, even out of state.

You have 3 choices: Return home early and go to court or hire an attorney to appear on your behalf. Your only other alternative is not to go, either personally or through counsel, and a default judgment will be entered in your absence. The last option is not good. Find a way to come to court.

Check with local atty. Usually proper service requires more than just a letter.

I agree with the others: even if serving the court papers was wrong, it is a technical process to have the service voided and to require you to be served properly, so you should find in-State counsel to help you with this.