Convert OST file to PST file
I still see questions in the forums from time to time where someone is asking if it is possible to convert an OST file to a PST file. This is usually due to a mailbox being deleted, but the OST file remains.
Microsoft does not provide any mechanism to convert an OST file to a PST file. However, if you can open up the OST file when you open Outlook, you can create a new PST file and just export email to it or drag-and-drop items in to the PST file.
There are a few third party tools that will do this, but I have not tested any of them.