To manually convert an OST (Offline Storage Table) file to PST (Personal Storage Table) format, you can follow these steps:

Create a New Outlook Data File (PST):

a. Open Microsoft Outlook on your computer.

b. Go to the "File" tab and select "Account Settings" or "Account Settings > Manage Profiles" (depending on your Outlook version).

c. In the "Account Settings" dialog box, go to the "Data Files" tab.

d. Click on "Add" or "New" to create a new Outlook Data File (PST).

e. Choose the appropriate PST format for your Outlook version (e.g., Outlook Data File or Office Outlook Personal Folders File).

f. Specify the desired location and name for the new PST file.

g. Click "OK" or "Finish" to create the PST file.

Export OST Data to the New PST File:

a. In the Outlook application, go to the "File" tab and select "Open & Export" or "Open."

b. Choose "Import/Export" or "Import" from another program or file.

c. Select "Export to a file" and click "Next."

d. Choose "Outlook Data File (.pst)" as the file type to export and click "Next."

e. Select the top-level folder of your OST file (usually the mailbox name) and enable the "Include subfolders" option.

f. Click on "Browse" to specify the location and name of the newly created PST file.

g. Choose the desired options for handling duplicates or replacing items (if applicable).

h. Click "Finish" to start the export process.

Wait for the Export Process to Complete:

a. Depending on the size of your OST file, the export process may take some time.

b. Outlook will display a progress bar and notify you when the export is complete.

Access the Exported PST File:

a. Once the export process is finished, you can access the exported PST file in Outlook.

b. Go to the "File" tab and select "Open & Export" or "Open."

c. Choose "Open Outlook Data File."

d. Browse to the location where you saved the PST file and select it.

e. The PST file will appear in the Outlook folder list, allowing you to access its contents.

By following these steps, you can manually convert an OST file to PST format using Microsoft Outlook's built-in export feature. It's important to note that this method requires you to have access to the original Outlook profile that was used to create the OST file.