Under c:\Users\<username>\AppData\Local\Thunderbird\Profiles we had just 2 files: <random1>.default-release and <random2>.default. Default makes sense, but I never knowingly generated default-release, and don’t know where it came from. Substituting “Roaming” for “Local”, we find exactly the same two file names, but of greatly different sizes. This immediately raises the question: how does one specify/choose between the two pairs of identically-named files, when source locations are not indicated? These were represented on the “Thunderbird – Choose User Profile” screen as “default-release” and “default”, with no sizes nor indication of the parent directory. Attempting to start Thunderbird with “default” just resulted in an invitation to open an account. Starting with “default-release” resulted in normal operation, with all recent emails represented. So far, so good, but now the fun begins. The “Choose User Profile” screen offers to Create, Rename, or Delete a profile. I Renamed the –release file by appending an .x. That renamed file – default-release.x – did not show up in any profile directory listing, even though I closed out and re-started, in case the change might require a re-start in order to display. Upon re-starting Thunderbird, the changed name did show up on the “Choose User Profile” screen, and starting with it was indistinguishable from when the name did not have the .x. But, it still does not show up in any Profiles subdirectory under its new name. I then Created a new profile with the name “CreatedProfile”, without putting anything in it. Trying almost immediately to delete it, Thunderbird indicates that it is lodged in the Roaming subdirectory, which was somewhat interesting in that I had not been asked which subdirectory I would have liked to have it placed in. Deleting “CreatedProfile”, which had been untouched/unused, caused chaos to erupt. It was apparently deleted all right, but caused some 35 previously-unseen files, and a few more subdirectories, to appear in the Roaming subdirectory. It is as if some subdirectory has been expunged, with its subdirectories moved up one level. \roaming\thunderbird now has only these 4 items: no profiles per se, and no Profiles subdirectory. installs.ini profiles.ini Crash Reports (subdir) Pending Pings (subdir) Not surprizingly, Thunderbird refuses to start, reporting: Profile Missing – Your Thunderbird profile cannot be loaded. It may be missing or inaccessible. This behaviour looks something like a “hidden file” problem, but “View – Hidden Items” is checked. I believe that this is a global setting, but even if it isn’t, I have inspected it on all drives, and it always shows as checked. The OS is: Win 10. And the questions are: is there any way for me to recover from whatever has gone wrong here? Is the profile, with all my most recent emails, sent & received, gone forever? If not gone, how can I recover that working profile when I can’t see it anywhere? If I import a profile from a Win 7 laptop and place it here in AppData\Roaming\Thunderbird\Profiles, or AppData\Local\Thunderbird\Profiles, will Thunderbird be able to find and recognize it? Doing that would cost me the most recent emails, but would be better than doing nothing. Since there is no apparent way to specify the location of the desired profile to the Choose User Profile screen, should I put a transplanted profile into Roaming, or into Local, or does it not matter?