Outlook PST file may gets corrupted due some issues like virus attack, improper system shutdown, hardware and software failure, etc. In such situation you to use Inbox Repair Tool for repairing Outlook PST file. It is a free utility provided by Microsoft. If your PST file is highly corrupted then you to use SysInfoTools PST Recovery Software.
For more information, see this article:- Easy way to repair Outlook PST file.