Hi gurus,
Note: I’m fairly fluent in pc, but I flunked (actually never took) Email 101. When it works, it’s simple and who cares? Now I do!
I recently allowed Win 10 to update prior to shutting down my pc, forgetting that I had previously also downloaded a Thunderbird update (but not run the .exe file. maybe it ran by itself on shutdown?) To allow both at the same time? I know, dumb, dumber and dumbest.
When I returned from a trip, the pc was restarted, everything was fine except for my email and contact files and data.
Thunderbird: had no contacts, no emails, no files and no history, including all saved email conversations. Profiles appear to be empty and files at: “C: Windows/Users/MyName/AppData/Local/Thunderbird/Profiles” only have non-related files. Contacts now include the few addresses I have mailed to since restarting the pc, nothing else.
Outlook: (seldom used) same results as T-bird.
Gmail: Current emails shown for 1 gmail account only (I have 2, plus formerly, gmail linked to several other non-GOOGL accounts too) no former or saved emails, files, folders or accounts, although the top-tier folder headings for saved files are visible (& empty.) Sub-folders are gone. Contacts are visible and appear to be accurate. I can show Google Contacts, but having searched for information on where Google contacts are located, I have found nothing. Perhaps they are in the Google Cloud. Perhaps they all came from my phone (Google Pixel6Pro?)
IONOS: Results unknown. I have several binding contracts and legal documents archived there, and am so far unwilling to risk having them go <poof!> like they have in the other programs .
Thunderbird is my most-used email app, but I also use GMail and IONOS, where I have other email accounts. All but Google show no contacts, no historic files of any kind.
Questions in order of Priority (Sorry there are so many, but I’m in real trouble here. :))
- Does the above info indicate to a pro, what might have happened to my emails and contacts, or if still there, where they are located?
- Do you know what folder/file combo any of these programs link to read contacts? Do they use a common file, or synch to/from separate files for each program? Web searches indicate many conflicting answers here for every program, except Google, who apparently won’t tell anyone where they store contacts; perhaps they change constantly? Perhaps no one knows?
- My pc is always backed up but I haven’t been able to determine which folders or files to restore, and what programs use what file for contacts and email bodies. Advice?
- In the future, I would like to copy, clone and backup my email files and contacts separately on a separate disk. What files are they?
- How can affect so many programs in so many ways?
Bonus Questions: Why is email so inaccessible and obscure? Why are email file names created from strange symbols an meaningless characters? Is everything email-related encrypted? If so, why? Why not just have a text - or even encrypted if necessary - file called “Contacts” that any program can use, if that is your preference? I mean, my email is important, but my data is not labeled “Top Secret” by anyone, and neither am I under any indictments.
Any help you can offer will be greatly appreciated. And if you think I’m being lazy, or looking for a shortcut, please reconsider. I’m finding that very few people know much about email files, where they’re located, or how they work or synch. That’s not any excuse for being so uninformed about email. I promise you I will become better informed. But first, I need to solve this little jam I created with help from my friends at Microsoft and Mozilla.
I will follow up on any recommendation of email primers - book, video, podcast, whatever. (Please save my a$$ first.) 
Thanks in advance!
Dan