For the large bunch of Outlook PST files, You have to go for some OST to PST Recovery Tool. If you have no idea or still confuse which one to go for, then you may try EdbMails OST TO PST
Converter. The OST to PST Converter
Tool exhibit some of the unmatchable features.
Some of its Features are
- Repairs Corrupted OST files
- Ultra-fast export of mails from OST to PST
- Allow Saving of OST files in different Format
For demo version visit: Free OST to PST