How to open Outlook when its unable to start

Safe Mode

If Outlook worked correctly the last time and nothing has changed about your account configuration, then checking if things work correctly in Safe Mode is a good first step. Starting Outlook in Safe Mode will prevent some or all add-ins from being loaded, prevents several settings files from being loaded and turns off the Reading Pane.

To start Outlook in Safe Mode you’ll need to start Outlook with the “safe” switch;

• Windows 7
  Start-> type; outlook.exe /safe
• Windows 8
  Start Screen-> type; outlook.exe /safe
  (just start typing, a search box will automatically become visible)
• Windows 10
  Start-> type; outlook.exe /safe
  (just start typing, a search box will automatically become visible or type in the command in the Cortana Search box)
• All Windows versions
  Hold the CTRL button when clicking on the Outlook button to start it. You will get prompted whether you want to start Outlook in Safe Mode.

When typing, please note the space between outlook.exe and /safe.