Backup up the Outlook Datastore File

To back up your data file which include all Outlook Tasks please do the following:

Open File - Account Settings

Select the "Data files" and observe the Location of your main account

Open the location of that file in Windows Explorer (Win+E) and copy-paste that file to a location of your choice

Restoring

If you at a later point want to restore that backup, simply exit Outlook and copy-paste the backup file back replacing the current .ost file
Amazon