Outlook search bar missing issues could be brought on by an out-of-date application, an indexing fault, or another issue. When Outlook search is broken, updating or adjusting index locations and features may fix it. A built-in repair tool in Outlook may also be able to help with the problem. 

Here’s how to go about it:

 Step 1: Launch the Outlook program. 

Step 2: Right-click the Home tab, and then from the menu, select Customize the Ribbon.

Step 3: Change the Popular Commands selection to Tool Tabs in the Outlook Options box.