How can one absolve oneself of debt owed to unknown or deceased individuals when it is impossible to ascertain their whereabouts or deliver the money to them?

You must investigate your debts and strive to deliver them to their owners or their heirs. If you do not know them or despair of reaching them, then give charity on their behalf.

Debts remain binding upon you until you repay them or are forgiven. You are permitted to take zakat to repay them.

If you intend to repay the debt, Allah will help you.

Recite abundantly the well-known supplications for repaying debt.