How to Restore an Outlook OST File Manually The following methods may be used to recover emails from OST files. Follow the instructions below to do the same: First Approach: Archive To archive all mailbox data to a local storage file, follow these instructions. Let's look at it: Start by opening the Outlook programme on your local computer. After that, choose the Archive option under the File menu. Browse the place where an Outlook.pst file may be stored after that. Finally, choose Finish to start the archiving process.