If the Personal Folders file (.pst) or Offline Folder file (.ost) will not open or if either is suspected to be corrupt, refer to the following applicable article for repair procedures: Outlook 2010 http://office.microsoft.com/en-us/outlook-help/repair-outlook-data-files-pst-and-ost-HA010354964.aspx Outlook 2013/2016 http://office.microsoft.com/en-us/outlook-help/repair-outlook-data-files-pst-and-ost-HA102749454.aspx