This advice might come too late, but, don't exit Firefox! Or if you already did, don't start it back up again!

If Firefox is running: Open your current 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 a new window listed various files and folders. For best results, change the view to "Details".

(If Firefox not running, get to this folder by pasting the following in the Run box on the start menu and pressing Enter: %APPDATA%\Mozilla\Firefox\Profiles and then double-click into the most recently updated semi-randomly-named folder you find there.)

In the window that launches, scroll down and double-click into the sessionstore-backups folder. Save all files here to a safe location, such as your Documents folder, so Firefox doesn't overwrite them. We may be able to use them to recover your lost tabs.

Also, if you return to the main level of the profile folder, you may find some sessionstore files. Copy those to the safe location as well.

Could you report back on what you found?

Note: If Windows hides the .js file extension from you, you can change a setting so that you can see all file extensions (this helps when renaming files). This support article has the steps: http://support.microsoft.com/kb/865219 or http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

The kinds of files you may find among your sessionstore-backup files are:

• recovery.js: the windows and tabs in your currently live Firefox session (or, if Firefox is closed, your last session)
• recovery.bak: a backup copy of recovery.js
• previous.js: the windows and tabs in your last Firefox session
• upgrade.js-build_id: the windows and tabs in the Firefox session that was live at the time of your last update

Thank you very much for your reply!

I have opened the Firefox 3 times since the accident. But at the first opening the browser I have saved sessionstore.bak and sessionstore.bak-20140923175406(from the nahd6ha2.default folder) and the whole sessionstore-backups folder too: previous.js recovery.bak recovery.js upgrade.js-20141027150301 upgrade.js-20141105223254 upgrade.js-20141106120505 upgrade.js-20141125180439 Will it help?

Great work!

The sessionstore.bak files are old, probably from around the time you installed Firefox 33 when the sessionstore-backup folder was added.

To try using one or more of the files in the sessionstore-backup folder, here's the process:

(1) Exit Firefox and it should create a sessionstore.js file in the main level of the profile folder.

(2) Rename the sessionstore.js file to sessionstore.old, or if you think you'll never need it, delete it.

(3) Copy in recovery.js or previous.js and rename it to sessionstore.js.

(4) Start Firefox and try Restore Previous Session. Are those the tabs you want? If not, you could try one of the other files from your backup of sessionstore-backup.

If none of the files has the missing tabs, you could try a recent Windows restore point. This is trickier on Windows 8 than on Windows 7, and you might benefit from using a third party utility. These were mentioned in another thread:

• http://nicbedford.co.uk/software/systemrestoreexplorer/
• http://www.shadowexplorer.com/

Or... I read about a roundabout way to get Previous Versions on the Properties dialog in Windows 8. I can't test this myself, but here's what you do:

In the address bar of your Windows Explorer dialog, replace the current path with the following and press Enter:

\\localhost\c$

Then click at the end and tack on the following (with your username) and press Enter:

\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

That should get you in the vicinity of your profile folder. Then you could right-click sessionstore.js > Properties > Previous Versions, or try one of the files in sessionstore-backups.

Unfortunately it restored ad page with no tabs in it. The option with resenting Windows would be too much, other ways didn't worked out. I guess I shouldn't have closed the browser. jscher2000, thanks for your time!

Actually, I do not recommend using System Restore. I don't trust that feature! Instead, you would be looking for a sessionstore.js, or recovery.js, or previous.js that Windows saved the last time it created a restore point and rescuing just that file. It might have been in the past week since Microsoft issued its monthly updates last Tuesday (if I recall correctly). If you think that is worth exploring, then you could try the tools I mentioned earlier.