How to repair your Outlook Personal Folder (.pst) files
At times you may find your Outlook .pst files are corrupted and that you are unable to access them. Corrupted PST file prevents you from sending or receiving emails and results in loss of important email data. In order to resolve PST file corruption, Microsoft has provided the Inbox Repair Tool, which lets you recover folders and items from corrupted Personal Folders (.pst) files.
Video: Sync OneDrive for Business to your computer
Sync OneDrive for Business to your computer and then access your files from File Explorer instead of from a web browser. All updates sync to OneDrive for Business or site libraries whenever you’re online.