First, you should contact a local attorney well versed in Fair Debt Collections Practices Act (FDCPA) cases.
From this very brief description, it sounds as if they are just demanding payment and you should write the law firm disputing the validity of the debt and assert that you paid the debt.
Some states (my state (NC) for example) treat worthless checks as a crime. But, there is a two year statute of limitations on filing a criminal complaint. Similarly, there may be a civil statute of limitations as well.
By answering this question, general information is provided and no attorney-client relationship is established. For specific inquiries, you should consult with experienced counsel in your area.