use a command line switch in invoke the profile manager. https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options#-ProfileManager_or_-P

I have done that but the only profile that shows up is the new one that was created. I had modified the profile.ini file to add in the other profiles. I looked at what was in the file and added in the rest of the path to the profile. With that change it seems that I have my old information back along with the e-mails that had come in since the crash. Do you know when the calendar link was added to TB? The first time that I had seen that info was after TB crashed and couldn't find the old profiles.

The calendar is the add-on lightning that is shipped with Thunderbird. The shipping started some years ago. About two or three major releases ago.

Thanks for the response Matt. I wonder why it had not shown up as an obvious element prior to TB crashing and forgetting its previous life?

When you install Thunderbird now, it tells you about the calendar, offers you a paid account with some mail provider that I forget and offers to add your existing accounts. It also checks (or did until they were disabled to stop crashes) if Eudora or Outlook were installed and offer4s to import from them if they were. A check for the default mail client and an offer to make Thunderbird the default is also part of that process.

This is what I have seen called the "first run". Once this is done you don't get told anything about any of those things as they should be finalized in that first startup. This a done by setting a hidden preference in the config file (there a lots of preferences there you will never see outside the config editor)

When Thunderbird looses the plot (it's profile) one of the things that is no longer available are all your preferences as they are stored in the profile, so you go back to a "first run" scenario.