If you’re sued by a debt collector, don’t ignore the lawsuit. Respond to the summons by filing a written response with the court. You should also gather any documents that may show the debt is invalid or already paid. If you fail to respond to the lawsuit, the court may issue a default judgment against you. Respond to the lawsuit and follow the advice of the California Courts Self-Help Guide and How to Respond to Debt Collection Lawsuit published by the Sacramento Library.