I "permitted" thunderbird update 60 this noon, and all my folders and mails have gone, plus my theme & features, what's essential too, because my eyes can't stand. the current appearance, -"dark" theme only adds another frame, but the message pane is still the same. I 've been reading and exploring whole day long, used system restore, which also didn't restore my theme!, they simply declared it incompatible, and gone, -instead of at least keeping it renamed and telling where!-, as is with my folders and mails, incredible! I am not helped by reading other Q & A, mostly dealing with much older versions. It is unbelievable that mozilla/thunderbird/ can have the right to affect my personal PC to this degree without notice! I read first what's new, and thought some features might be useful ..., now I desperatly wasted my time and still no way to restore. Thanks in advance for a real solution!