I owed money more than 20 years ago and never paid it back. Is there any real letter?

And letters of credit.

Even if it was owed 20 years ago, the bank will keep loan records. Although the credit information system was officially used in recent years, the personal loan information saved by banks can be uploaded and registered. If it is not returned for a long time, the bank will handle it through formal legal means, including credit investigation.

Credit investigation refers to collecting, sorting, saving and processing the credit information of natural persons, legal persons and other organizations according to law, providing credit reports, credit evaluation, credit information consultation and other services to help customers judge and control credit risks and carry out credit management activities.