The main Firefox profile folder s in AppData\Roaming. The location in AppData\Local is used for the disk cache and some other data.

Did you lose the tabs from a previous session?

Did Firefox crash or did this happen when Firefox updated or otherwise?

The sessionstore.js file in the profile folder is used to store session data, but is only present when Firefox is closed. The sessionstore.js file is created from recovery.js when you close Firefox and sessionstore.js is removed and copied to previous.js when you start Firefox.

You can backup the session files in the sessionstore-backups folder in the Firefox Profile Folder to make sure not to lose possible important session data.

previous.js (cleanBackup: copy of sessionstore.js from previous session that was loaded successfully)
recovery.js (latest version of the sessionstore written during runtime)
recovery.bak (previous version of the sessionstore written during runtime)
upgrade.js-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.js to replace the current file (make a backup copy of the current sessionstore.js).

You can also try to restore a previous version of the sessionstore.js file.

• Right-click: Properties > Previous Versions

• http://windows.microsoft.com/en-us/windows-8/how-use-file-history

Note that best is always to use "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit) to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

Open the History Manager <Control><Shift> H. In the search bar, enter the name of the site.