I was able to access it by History to Recently Closed Windows but I still don't understand why it didn't show the restore previous session box.

Hi Brian, it's not normal for Firefox to start up with the crash recovery page -- unless Firefox typically crashes every time you shut it down AND Firefox was unable to do an automatic restore.

For a seamless session restoration, you can change your startup setting on the Options page. See: Startup, home page, tabs, and download settings.

If you prefer to start with the list of your previous session windows and tabs, you could try making about:sessionrestore one of your home page(s). Or if you don't want to see it that often, you could bookmark it for quick access.

(Note: internal about: page addresses do not take http:// or https:// at the beginning.)