A few suggestions, though I’m not sure which (if any) will work for you.
Rollback the Windows update to a previous update. You MIGHT find your file, though that’s the least likely.
Go to your backups and search for a *.pst file. (Unless you’ve fiddled with names or opened various versions, it should be named OUTLOOK.PST. You’re looking for a file dated prior to this update. Rename your current PST file to something like Outlook.PSTOLD and replace it with the older file you found. Your PST files are re probably in a directory named C:\users\yourname\documents\outlook files.
Search your drive for all *.PST files. You may be able to spot a backup of your current outlook file. Replace the bad one and use the good one.
All that said, not to be too much of an ass here, it’s always a good idea to make frequent backups of your Outlook files. The program has a less-than-stellar reputation of maintaining all your information….