See: Restore previous session - Configure when Firefox shows your most recent tabs and windows

Nothing that I could make use of...

I've found a file called "sessionstore.bak" which, using notepad, seems to contain a great deal of URLs, could it be containing my targeted tabs?

Problem is, it's 64 thousand characters long, so manually eliciting addresses from the file is infeasible.

you can enter about:sessionrestore in the Location Bar (address bar) to force the Restore Session page to appear, after first restoring a backup file to restore the old session data. The session data is stored in sessionstore.js; this file can be restored (while Firefox is not running) from backups, including "sessionstore.bak". The file "sessionstore.bak" is created if you launch Firefox after a crash has occurred. It is a copy of the current sessionstore.js that gets lost otherwise, if you restart Firefox.

http://forums.mozillazine.org/viewtopic.php?p=4655235#p4655235

http://kb.mozillazine.org/Session_Restore

See previous reply

Not feeling good... the .js file doesn't contain anything to restore, and the .bak file restores only the single window that I already have, without the other four missing windows...

I don't think there are any deeper levels of backups than these two files, is there?

Yeah, that's as deep as you can go for the most part.

Are you using "Show my windows and tabs from last time"?

Tools > Options > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time"

Also you might give this a shot:

type in the address bar about:config & select i'll be careful i promise

type in the address bar: browser.sessionstore.max_tabs_undo & right click > modify > type 0 > OK

Restart Firefox & repeat for: browser.sessionstore.max_windows_undo

If you still don't have any luck then either you can read up further in the links I provided earlier or give up on finding and/or restoring the sessions you are looking for.

The first option is already enabled in my case, the second and third options inside the CONFIG do not yield any results. I believe you were hoping that a ZERO would represent INFINITY, but it doesn't, it represents a disabling of the functionality.

This will give you a great deal of information & support that isn't found in the standard Firefox support forums & for the most part relatively obscure.

1. Visit http://kb.mozillazine.org/Knowledge_Base

2. Locate Search on middle right side of page & type in "Session Restore" without quotes

3. Look through the applicable results that are returned.

Note: The results & information found using Mozillazine is for the more advanced user, and provides more in depth technical information. Judging from your responses I'm sure you will have no problem with the information.

The search results detail the process of session storing and restoring, and describes what the values in about:config does. It's mostly preventive stuff though, doesn't add into recovering my stuff, but I believe you were aware of that.

I've installed two add-ons, "Nightly Tester Tools" and "Session Manager", to prevent this thing from happening again.

Use "Firefox/File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit") to close Firefox with all open window if you are currently doing that by clicking the close X on the title bar. Using the close X only closes that window and thus only the last closed window gets restored.

Been through that.