When assessment rolls or treasurers' books, in whole or in part, of any county, town, city, village or district shall be lost or destroyed by any means whatever, a new assessment, or new books as the case may require, shall be made under direction of the county board. The board shall, in such cases, fix reasonable times and dates for performing the work of assessment, equalization, levy, extension and collection of taxes, and paying over the same, or making new books, as the circumstances of the case may require. The dates fixed by the county board shall conform to the dates required by law for similar purposes. The county board is fully empowered to select and appoint persons where it may find the same necessary to carry into effect the provisions of this section.