re :I deleted messages in Allmail folder

This sounds like a 'gmail' account.

gmail stores all of your incoming and outgoing mail in the 'All Mail' folder, so gmail also uses it as an archive.

Labels are applied to the emails in the 'All Mail' folder eg: Inbox, important etc, so offering a view which appears to show them in folders of your choice. If you delete emails from the 'All Mail' folder then you are removing them from all other 'folders'; you are removing them off the server.

To put them back you would need to use a backup created prior to deleting emails. Do you have a backup?

It is gmail. The intended and successful deletions in allmail were for dates prior to 1-1-17. It apparently also removed emails from my inbox local folder for all this year. I had a backup of 2016 and before but not for this year. Other local folders containing filtered emails were not lost.

Please explain what you mean by "inbox local folder".

I suspect that you need to learn about IMAP and the interconnectedness of your "local" folders and those on the IMAP server.

The folders in your gmail account that you see in Thunderbird are not complete and self-contained stores; they are views of what is on the remote server.

https://support.mozilla.org/en-US/kb/thunderbird-and-gmail

Unfortunately, the account settings option in Thunderbird to "Keep messages for this account on this computer" is a little misleading; it does make local copies, but they are synchronized to the server, and not permanent. These "local copies" are there to provide more responsive browsing and searching, and they provide access to your pre-existing messages when offline.

OK, but that still doesn't explain why my 2017 copies of Inbox have disappeared