Accessing the previous local directory, to re-install my sent folder on POP

Question

I am trying to re-install the sent emails from my POP-based email account.
The account was removed upon recommendation of a tech support person (not Mozilla!) in order to address a password problem. The tech support person thought I was using an IMAP account, and told me incorrectly that it would all re-populate when I re-installed an email account. All that is coming in are the "inbox" messages. I wish to re-instate my sent emails and really hope they are on my computer somewhere. As stated, I am using a POP-server for my email, and chose to store the messages on a local folder.
Is there a way to map to the previous local directory (or folder), which would have been the previous one, and therefore regain all my sent emails? I also have TimeMachine backups on an external hard drive, which I can access as well.
Some technical details: I am running Thunderbird 31.5.0 on a Mac 10.7.5 operating system.
Many thanks in advance. This is pretty nerve-wracking - the feeling I lost all my sent emails by removing an account...!, based on a well-intentioned tech support person.

Answer 1

I am on a Mac, and don't have an account online with backups.
But, working with an Apple technician, who is very helpful, we were able to figure out how to perform a Time Machine restore onto another computer - and then import those emails into my T-bird system. The problem now is that the ARCHIVE subfolders for my Thunderbird account ((all POP) where I archived old emails to allow enough space to handle new email) are now blank, with no messages.
QUESTION 1: Any thoughts for how to restore those subfolders, which show up blank, with no emails in them?
QUESTION 2: The technician could not find on my hard drive any of the folders containing emails for the deleted account. The INBOX populated automatically when I re-installed the account, but is missing a few earlier years of emails.
If this is a POP account, the records for those emails must be somewhere on my hard drive, right? Any thoughts for where one might find them? They aren't in the typical Library folder, and the technician went into a "hidden" library folder to try and find the email files.
Many thanks!