Where any assessments made and levied under this chapter cannot, for any reason, be enforced, and part of the work has been done, the county court shall proceed as to any or all lands benefited by the improvement in the same manner as if the appraisement and apportionment of benefits had never been made, in which event any payments already made shall be duly credited to those who have paid them.
T.C.A. § 69-5-811