It sounds like a CMS (Content Management Service) problem.
You don’t say what version of DS4 you are using (18.104.22.168?), or what OS, but since you mention a PC I will assume Windows of some flavour. Have a look in the Task Manager to see if the service called ContentManagementServer.exe is running. The search function relies on this service, and if it is stopped, you would need to restart it from Start > All Programs > DAZ 3D > DAZ Content Management Service, there are icons there for stopping and starting the service.
Obviously there is a problem, one way to fix it would be to uninstall CMS, then re-install DS4P, that way you will get the latest version of the CMS which is not normally re-installed with the main program.