Thunderbird usually opens straight onto the inbox. Yesterday it opened onto the home page which I have never used before. Now it will not allow me to enter any of the mail boxes or start a new message. The other options under the headings on the home page work but none of those under the heading Email work nor any of the in the tool bar at the top of the screen. The messages are there as when I use the search option those I have searched come up. How can I now unblock it or get into my mail boxes ?