C: drive croaked. Finally gave up and started with a from-scratch installation of Windows 10. All programs, OS, etc, on C:, all data on other logical drives. This notebook has 1TB of SSD, partitioned. So far so good. However I managed to delete essentially all email from one Thunderbird account; the other four are fine. Email is IMAP style. But deleted an entire set for one account, so the server did too. Carbonite has a complete copy of the entire Thunderbird folder (it has started over with my new installation), so looking for how to "simply" get all of the INBOX emails for one of the five accounts and import or copy them into my current TBird environment. Spent some time with the Carbonite folk; not much help. I did reinstall Carbonite, so I have the Carbonite Backup drive which they claim has the old file in it. I suppose the Carbonite "drive" is just an interface to all the data that is actually at their end. So I have about 3K email I need to recover from Carbonite, get into "new" Thunderbird. The old version is due to be deleted soonish, so some urgency.