The short answer is - the trial level court for your jurisdiction.
The long answer depends on a number of facts not presented, like the amount of damages in dispute, where the parties live, the nature of the agreement, local state laws, and others.
You should contact an attorney near where you live. Most attorneys provide a free consultation.
The statute of limitations and when the breach was discoverable are very FACT-SENSITIVE and your legal advisor will need more details. I will be happy to consult on your specific situation. The severance agreement might have arbitration requirements as well as venue/jurisdiction stipulations. Further, if the situation involves federal as well as State law, and if it involves more than $50,000, then you might choose federal court rather than State(county) court.
veRONIca jarnagin, atty, pc
veRONIca jarnagin, atty, pc 317-253-7664 provides this response as general guidance and not specific legal advice. If you wish to receive specific legal advice for your situation, please call to schedule an appointment.