Can you open OST file from outlook?
Click Tools -> Account Settings -> Double click Email account -> More settings -> Advanced tab -> select Use Cached Exchange Mode check box -> Click Offline Folder File Settings... and Click Browse -> Browse to .OST file -> restart Outlook.
After restart outlook, Click File -> Import and Export -> Export to a file -> Personal Folder File (.pst).
Method 2: Create a new Personal Folder File (.pst), drag the folder to .pst that you want to move.
Note: Dragging default folders, such as Inbox, Calendar, and Contacts, brings up a message that you can’t move default folders. The contents will be copied instead, with the folder named Inbox (1), Calendar (1), etc.
Or If you don't have this capability, then use Recovery Toolbox for Outlookhttp://www.osttopst.oemailrecovery.com/