Sorry for the delayed response!

First please copy the recovery.js, previous.js, and various upgrade...js files to a safe location such as Documents where Firefox won't replace them.

What happened when you tried History > Restore Previous Session? Or did Firefox show the "This is embarrassing" screen and you tried to restore windows and tabs from that screen?

When Firefox exits, it creates a file named sessionstore.js at the main level of your profile folder (not in the sessionstore-backups folder). When Firefox starts, it reads the sessionstore.js file and then deletes it. So... in order to get Firefox to read an older session file, after you exit Firefox, you would rename sessionstore.js to something like sessionstore.old, and copy in the relevant .js file and rename it to sessionstore.js. When Firefox starts, it should read that file and Restore Previous Session should use the contents of that file.

A couple tips if you aren't familiar with the profile folder:

(1) Please keep backups

(2) You can open your currently active Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch the folder in a new Windows Explorer window. sessionstore.js won't be here yet, but should appear after you exit Firefox.

To fully exit Firefox, you can use either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

It may take anywhere from several seconds to a minute before Firefox finishes updating profile files.

(3) By default, Windows hides the .js extension. To make sure you can rename files accurately, it is best to show all extensions. This article has the steps for that: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

(4) Windows 7 often saves older versions of these various .js files in restore points. If you right-click one of them, choose Properties, then Previous Versions, you might be lucky enough to find one from the relevant time frame. Please restore the file to a safe location such as your Documents or a new subfolder to minimize the potential for loss of recent data.

If you see the URL on the location bar then try to reload the tab by pressing the Enter key or possibly click reload. I've seen cases when tabs appear blank, but there is still the correct URL in the location/address bar. If the location/address bar is empty or about:blank then you are out of luck and need to check the backups in the sessionstore-backups folder.