When trying to access Help using the ? button in any SharePoint 2013 sites you receive an error: "Sorry, this site hasn't been shared with you." In order to solve this follow the below steps: 1. Go to central administration site /sites/help (ex.: https://CA/sites/help) 2. Click on "Site Contents" then on "Product Help" 3. Library settings -> Permissions for this document library -> click on "Help Group" and add the "NT Authority\Authenticated Users" group. 4. Refresh the page and it should work.