Ofice 365 outlook search refine options are greyed out

Marvin Oco 

The normal cause for that issue was a bug in Windows when upgrading from one major version of Windows to anther.  During upgrade Windows did not migrate the search registry settings.  Normally repairing Office will fix it.  The bug was fixed starting in this Windows 1709 update, https://support.microsoft.com/en-us/help/4093105 (search on search on this page to see the issue).  It does not retroactively repair the problem but prevents the issue in future upgrades.  

If repair does not work then this issue might also cause it, https://support.office.com/en-us/article/no-search-results-for-pop-imap-or-exchange-accounts-51c9d2c7-a3db-4358-afdf-50d3a9e57039.  You might need to delete some errant reg keys mentioned in the article.

The rest of the search troubleshooting is in this article, https://support.office.com/en-us/article/Troubleshooting-Outlook-search-issues-2556b11f-f4d8-46be-b0a7-de33a3f4f066.