How about:

• "3-bar" menu button > History > Recently Closed Windows
• optional "Library" toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

Also, Ctrl+Shift+N is the shortcut to reopen the last closed window.

If you cannot get your tabs back through the normal user interface, you may be able to extract a list from one of the many session history files Firefox saves. Problem is they tend to get replaced at startup, so please act quickly.

Do not exit Firefox, or if you closed it, don't re-open it.

(1) To open your profile folder...

If Firefox is still running:

You can open your current Firefox settings (AKA Firefox profile) folder using either

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

In the first table on the page, find the Profile Folder row and click the "Open Folder" button on that row (the other similar buttons are for other folders). This should launch Windows' File Explorer listing the contents of your current profile folder.

If Firefox is closed:

Type or paste the following into the Windows Run dialog or the system search box and press Enter to launch Windows Explorer:

%APPDATA%\Mozilla\Firefox\Profiles

In that folder, do you see a semi-randomly-named folder? If so, click into it. If you find multiple such folders, find the one that was most recently updated.

(2) Copy out session history files

In your profile folder, double-click into the sessionstore-backups folder. Save all files here to a safe location such as your Documents folder.

(3) What files did you find?

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

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update

Sometimes you can tell from the last modification time which one will have your missing tabs, but not always.

Optional File Contents Preview

These compressed files are a pain to view, so I created a tool on my website to list out their contents. If you want to try that, you can drag and drop it onto the large box on the following page, then click the "Scrounge URLs" button:

https://www.jeffersonscher.com/ffu/scrounger.html

If you don't get a list within 15 seconds, that probably means the script is caught in a loop. You may need to close the tab to avoid a tab crash and then try again in a new tab.

If you get a useful list, use the "Save List" button to archive it as a web page of clickable links for future reference, in case no other approach is successful.

Thanks for the answer but these tips did not help me get my tabs back

None of the session history files from your profile folder had the missing tabs?

In that case, we would need to move on to backups. Do you make regular backups of your computer?

Did you try to restore or at least check the most recent upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox) in the sessionstore-backups folder as that is usually the best chance for a lost session if this is about tabs you have used for quite some time ?

You can try to restore a recent upgrade.jsonlz4-<build_id> when available or use a utility to browse Windows System Restore points to see if you can find a recent sessionstore.jsonlz4 file.

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file with Firefox closed.

• make sure to backup the current sessionstore.jsonlz4

I tried as you suggested but none of it works

Can you explain in more detail where the problem is?

- No .jsonlz4 files were found in the sessionstore-backups folder - The .jsonlz4 files do not have the missing tabs - Firefox isn't reading/restoring the .jsonlz4 file that has the missing tabs after you make the file substitution - Some other problem