If your local OST files get damaged, and all the data that you need are stored in those OST files only, then in this case you need OST to PST Converter tool to get back your lost data that are saved in those damaged OST files.
There are so many tools available on internet but I would like to recommend you to use this classic OST to PST Converter Software which has interactive user friendly interface that allow all users can easily access this software without have any technical skill. It filter option help the users to sort the messages by date, contacts, size and etc.
Read more:- https://www.recoverfilesdata.com/blog/how-to-migrate-ost-files-to-outlook-pst-files/
Export mailbox as a PST file
Login to Outlook with the Exchange account that was used to create the OST files. And to export the OST mailboxes to PST, follow the simple procedure:
Go to Files >Open & Export and click Import & Export.
Select Export to a file; then click Next.
Select the second option—Outlook Data File (.pst)—and click Next.
Select the folder which you want to export and click Next.
Browse the location where you want to save the new PST file and choose the options regarding the duplicate items.
Hope this helps.