Converting an OST (Offline Storage Table) file to a PST (Personal Storage Table) file manually can be a challenging process, as OST files are meant to be used in conjunction with the email client (such as Outlook) and aren't designed for direct conversion. However, in certain situations, you might need to convert an OST file to PST, such as when you no longer have access to the original email account or need to recover data from a corrupted OST file. Please note that these steps might not work perfectly for all scenarios and should be approached with caution.

Here's a general approach to manually convert OST to PST:

Backup Your OST File:
Before attempting any manual conversion, make sure to create a backup of your original OST file. This is crucial to prevent data loss.

Create a New PST File in Outlook:
Open Outlook.
Go to the "File" tab.
Click on "New" > "Outlook Data File."
Choose "Office Outlook Personal Folders File (.pst)" and click "OK."
Specify a name and location for the new PST file.

Configure a New Outlook Profile:
Close Outlook if it's already open.
Open the Windows Control Panel.
Search for "Mail" and open the "Mail (32-bit)" or "Mail (Microsoft Outlook 2016)" option.
Click on "Show Profiles" and then "Add."
Follow the prompts to create a new Outlook profile and connect it to a new email account (you can use a dummy account for this purpose).

Import OST Data to the New PST File:
Open Outlook with the new profile you created.
Go to the "File" tab.
Click on "Open & Export" > "Import/Export."
Choose "Import from another program or file" and click "Next."
Choose "Outlook Data File (.pst)" and click "Next."
Browse and select your original OST file.
Choose the destination folder in the new PST file (usually your mailbox) and click "Next."
Optionally, choose to allow duplicates to be created or not.
Click "Finish" to start the import process.
Move Data to New PST File (Optional):
If you only need specific data from the OST file, you can manually move emails, contacts, calendar entries, etc., from the original OST folders to the corresponding folders in the new PST file.

Greetings,
Peter