Sharepoint - Sharepoint Designer 'All files' missing

The solution is simple:

When you enable SharePoint Designer at the web app level (by selecting the first checkbox to Enable SharePoint Designer), if you want the user to see the All Files menu item, make sure to also check the checkbox for Enable Managing of the Web Site URL Structure.

In central administration -> Select Web Application -->General Application Settings -> Sharepoint Designer

click on the Sharepoint Designer Settings option.