I have the hidelostitems system preference set to ON and try to search book on OPAC search result is No Result found when i have hidelostitems set to OFF to get any results in an OPAC search.Please guide me how to solve these problems and disables display of lost items in OPAC.

Take a look at this Koha FAQ entry: http://koha-community.org/documentation/faq/searching/#16 hidelostitems preference is similar to OpacSuppress.