Sue them and record a judgment lien. The lien will impact the client's credit rating for years, and may unexpectedly force him to make payment at some time in the future. In Connecticut Superior Court judgments are good for 20 years. The judgment liens need to be renewed every 5 years for the unexpired portion of the judgment. If your client has disappeared as you say you will need to check your state's statutes for service of process. It will differ depending upon whether your client is a corporation,LLC,partnership or a sole proprietorship.

it is a good idea to lay the groundwork for self protection when you initially accept business from a new client:

                           1.    Limit the amount of credit you will extend to them each month

                           2.    Operate with a written agreement.

                          3.     If you are dealing with a corporation or LLC try to get a corporate officer or managing member of an LLC to sign in his/her personal capacity (guaranty of payment) in addition to signing in his/her representative capacity.This will allow you to sue the individual as well as the corporation or LLC without having to pierce the corporate veil.

If the individual was careless in filling out the contract, and did not disclose that the business entity was a corporation or LLC and further failed to disclose that he was acting in a representative capacity as a corporate officer or manager of an LLC he may have rendered himself personally liable on the claim. In many states the law of agency requires that he disclose the correct identity of the corporation/LLC and that he is acting in the capacity of a duly authorized agent/employee.I just completed a number of arbitrations in which the individuals failed to write the complete name of the corporation/LLC on the contract and failed to indicate their job titles. The individuals were held to be liable on the claims, and their personal assets became subject to the payment of the claims.