The document you described is sufficient to provide evidence of the debt and the terms of repayment.  In order for a contract to be valid, it is required to identify the parties, subject matter, essential terms, time for performance (time for repayment in your case), and signed by the parties to the agreement.You may be able to file your lawsuit in Small Claims Court.  Your damages (monetary compensation you are seeking in your lawsuit) would be the amount owed plus interest and court costs.  Court costs would include the court filing fee and process server fee.