Check Search Options: In Outlook, go to File > Options > Search, and check the Search Options. Ensure that the folders you want to search in are selected. Also, make sure the "Include results only from" option is set correctly. Reset Outlook Cache: Sometimes, issues with search can be related to the Outlook cache.

Based on your preference, you can use Advanced Search by clicking the filter button on the right side of the search box. Alternatively, the Outlook ribbon will change to show the Search tab and you use any of the options in the Refine group to refine your search results.

Select the search bar, located above the Outlook ribbon. Type a name, subject, or phrase which is included in the email message that you want to find. You can use quotation marks around a phase to search on words in that exact order.