I will offer you two options:
First not a short guide for restoring .pst files - see it below
Second some useful resources which might help you if your .pst file awfully damaged and standard features can't help
http://community.office365.com/en-us/f/172/t/262226.aspxhttp://www.answerbag.com/q_view/3169137https://www.repairtoolbox.com/pstrepair.html Outlook Repair Toolbox
How to use Inbox repair tool on corrupted PST folders:
After receiving message of error attack or corruption, it is prime responsibility for user to handle issues adequately. The whole process of Outlook repair passes through following steps defined below:
Finding of ScanPST.exe: To initiate Outlook repair process, it is necessary to find out the exe file of inbox repair tool. Its location is predefined but varying from one version to another. Its path also depends on Windows bit like 32 or 64 as well as MS Outlook bit version.
In MS Outlook 2013, its path is:
MS Outlook 2013 x32:
Windows x32 C: Program Files/Microsoft Office/Office15
Windows x64 C: Program Files (x86)/Microsoft Office/Office15
MS Outlook 2013 x64
• Windows x64 C: Program Files/Microsoft Office/Office15
Click on EXE TO Execute Process: Just click on exe file then a dialogue box with name “Microsoft Inbox repair tool” appears.
Select Affected Outlook Data Files: Through browse option, it facilitates the user to select infected PST file.
Start Scanning Process: After selection of targeted file, user can start scanning process for spotted location in PST file by clicking “Start” option.
Detailed information of Error: After completion of scanning process, a new dialogue box appears with detailed information of existing error, number of folders and total number of items.
Make a Backup Copy of Outlook Data: It is recommended to maintain backup of PST file to avoid any kind of loss during repairing process.
Start Repair Process: With click on “Repair” button, this utility starts to repair the damaged structure of PST file in adequate way. It has 8 phases during repair operation.
Process Completed: As soon as repair process is completed then a dialogue box shows the message i.e. “Repair Completed”.
Time limit depends on the nature of corruption and size of infected PST file. In case, you PST file seems nearby 5 GB then it can take up to 45 minutes to complete repair process.