Why is my Outlook search not working properly?

Outlook search not working can happen due to various factors including unfinished index creation and out-of-date software programs in addition to damaged PST/OST files. Some conflicts occur between add-ins and antivirus programs that affect Outlook performance. Outlook search functions can return after restarting the application and updating programs while making sure the Windows Search index completes its process. The Outlook search functionality can potentially recover through rebuilding the index and data file repair operations when search persistence occurs.