It is because of any problem, such as file oversize, unexpected system shut-down, file header corruption, disrupted compaction etc., your Outlook PST files have been badly corrupted and thereby have become completely inaccessible.
Don't worry! For any of the above or similar cases of PST file corruption, Stellar PST recovery software can help you in repairing the damaged PST files and successfully recovering all your precious mailboxes.
The software incorporates advanced recovery techniques and is an immensely useful utility in recovering the entire Outlook PST items. With easy-to-understand interactive user interfaces of the software, the recovery operation can be performed in few simple steps.
Below screen-shots will give you a clear idea on how to proceed with the PST recovery process: