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 structure of OST file.
If unable to repair .ost file by Inbox Repair Tool, then you should use third party application like OST file repair
tool that helps you to repair corrupted .ost file and save it into .pst file format easily.