Have been using Thunderbird for some time. All of a sudden today, all of the read messages in the Inbox disappeared. When I open a new message, read it, and then close it, it disappears. At the bottom of the window, it shows the number of unread messages and the total number of messages in the Inbox. I cannot access the read messages. I have tried to look at all the settings that might have inadvertently gotten changed but cannot find anything that might correct the situation. Does anyone have suggestions to help correct this? Thanks. Rich