Before you bother repairing OST files using third party solution, please read the following:
Take a look at versions of Microsoft Outlook you are using. So here are two fixes that will depend on your situation.
- OST Integrity Checker Tool is used in earlier versions of Outlook(2007,2003,2002) to repair OST file.
- Inbox Repair Tool is used in Outlook 2010 and other newer versions of Outlook to repair internal data structure of OST file.
Technical detail is available here; http://www.ostpstsoftware.com/blogs/what-is-inbox-repair-tool.html
If you not that lucky as was the case with me, you will have to recreate OST file!