The steps are basically the same for all versions: • Close Outlook and any other open Office applications • Open the Control panel or Settings • Find Add or Remove Programs • Select the Office installation (or Outlook, if using standalone Outlook) • Click the Modify, Change or Repair button • Select the desired repair option and complete the wizard For the steps and screenshots specific to older versions of Outlook, see: Office 2013 & Office 2016 Use the Repair process in the Control Panel's Programs and Features or Windows 10 Settings. You can open it by typing Add or Remove Programs on the Start screen or in Search. In Windows 10, open the Control Panel then find Programs and Features or Add or Remove Programs. Quick Repair will check files and replace missing or potentially corrupt files.