Do you mean you can see thumbnail images of your open tabs along the Windows Taskbar, but clicking one does not open that window?

Sometimes Firefox's window gets "off screen" somehow. You often can force it to appear on the screen by right-clicking the little thumbnail image above the Taskbar and choosing Maximize. Does that work?

One possible cause for this is that the file which stores window sizes and positions has become corrupted. You can remove that file and Firefox will return to standard window sizing/positioning.

Method #1: If you can get a maximized window:

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 listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

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

Pause while Firefox finishes its cleanup, then rename xulstore.json to something like xulstore.old. If you see a file named localstore.rdf, rename that one to localstore.old.

Start Firefox back up again. Do windows display normally again?

Method #2: If you cannot get a Firefox window at all:

Shut down Firefox by right-clicking the taskbar icon > Close All Windows.

Using the Run dialog (windows key + R) or the Start menu search bar type or paste the following and press Enter to drill down to the Profiles folder:

%APPDATA%\Mozilla\Firefox\Profiles

Here you may see one folder -- in which case, double-click into that -- or more than one folder -- in which case, double-click into what looks like the most recently updated.

Scroll down and rename xulstore.json to something like xulstore.old. If you see a file named localstore.rdf, rename that one to localstore.old.

Start Firefox back up again. Do windows display normally again?

Then, to turn different bars back on, you can use one of these methods to show the toolbar list and select the desired bars there:

• right-click a blank spot on the tab bar (or the "+" button)
• tap the Alt key to activate the classic menu bar > View > Toolbars
• in Customize mode > Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

To turn on the Menu Bar, Bookmarks Toolbar, or other bars, click it on the list.

Thank you, that is exactly it; I see a thumbnail image of an open tab along the Windows Taskbar. I cannot open it, nor close it by right clicking. I followed your instructions anyway, though it wouldn't close. I renamed the xulstore file, then closed that window. There was not a localstore file

The problem remains.

I'm basing the following on Windows 7; there may be differences in Windows 8.1.

When you right-click the thumbnail image itself, one of the choices should be Maximize. Is that available? If not, Windows thinks it already is maximized. If it is available, does it work?

When you right-click the taskbar icon (the Firefox icon, not the thumbnail), you should get an option for "Close all Windows". Does that work? If so, try the file rename again since Firefox might have re-saved the problem settings at shutdown.

I am using Windows 7. When I right click the thumbnail itself, I see no options and nothing happens. It just goes away.

When I click the Firefox icon on the taskbar, I see "close window" but not "close all windows." I click "close window" but it doesn't. The thumbnail goes away.

xulstore is still .old but I redid it anyway. No change.

I sure appreciate your efforts, thank you very much! Any more ideas?

Can you tell whether Firefox is completely shutting down when the thumbnail goes away, or is it just hidden because you aren't mousing over the icon any more?

If necessary, you can kill/crash Firefox using the Windows Task Manager. Press Ctrl+Shift+Esc to call that up. On the Applications tab, if you find a Firefox window there, try highlighting it and using End Task. This may take several seconds while Windows determines whether it can shut Firefox normally or whether it is frozen and not responding. If this ultimate does not work, you can switch to the Details tab and find firefox.exe here, highlight it, and use End Process.

Once Firefox is completely shut down, check whether xulstate.json is still gone and start Firefox again.

Great idea, I hadn't even thought about Task Manager. I went there, and found Firefox running. It said it was waiting for a response from me. I ended the task and the thumbnail went away. I then found that xulstate.json had come back. I changed it to .old2 and then checked to be sure it was still changed. Then I tried again to open a new Firefox window. Again it is a thumbnail! And again in Task Manager it said it was awaiting a response from me.

I know what caused this, I think. Before this happened, I was at a web site where I clicked on the link to email them. It opened Outlook. I have Outlook installed, but I don't use it. I closed the program. Then a message box kept popping up over and over, asking me if I wanted to allow this change to my computer. Every time I clicked no, and closed the box. Finally I closed it and hurried and rebooted before the box could open again. I am sure it was after that, that my Firefox tabs were thumbnails.

Well, I have been using another browser for 4 weeks and am sick of it. I want my Firefox back. I uninstalled Firefox, rebooted my computer, and reinstalled Firefox. It still won't work!!!

Now I again have thumbnail images of the open tabs along the Windows Taskbar, and clicking one does not open that window, but instead it flies away quickly to the right and out of sight

What can I do?!

Could you try to do a "blind" shutdown: click one of the thumbnails to activate the off-screen window, then press and release each of these keys in sequence:

Alt f x

(That should trigger File > Exit from the menu bar)

Does Firefox close?

If not, does it work to close each of the thumbnails (not sure if Windows 8.1 displays a little x when you hover them like Windows 7).

Assuming you can get Firefox to shut down, try using Firefox's Refresh feature, as follows:

Hold down the Shift key when starting Firefox.

A small dialog should appear. Click the "Refresh" button. Firefox should display a small confirmation dialog explaining that this will remove your add-ons and restore default settings. For more information on Refresh, see: Refresh Firefox - reset add-ons and settings. Approve the Refresh if/when you are ready to proceed.

Any improvement?

Alt f x worked, thank you. The thumbnail windows closed.

I pressed the shift key when I tried to re-open Firefox, and I got the dialog box. There was no "refresh" option. The options were:

Restore move (greyed out) size (grey) minimize (grey) maximize New tab reopen closed tab Task manager close

I tried Restore, and nothing happened. I tried again by choosing Maximize, but again nothing happened.

Hmm, I don't recognize that menu. Part of it sounds like the window control menu you would get if you are looking at a window and press Alt+Spacebar (Restore, Move, Size, Minimize, Maximize). Why that would be mixed together with the other items is a complete mystery to me.

If you have Firefox pinned to the Taskbar, could you unpin it or use a desktop shortcut, holding down the Shift key while double-clicking the shortcut?

I unpinned Firefox from the taskbar. Then I held down the shift key while double-clicking the Firefox icon on my desktop. All that did was put the Firefox icon back on my taskbar, with the thumbnail window again.

Hmm, not sure why it's so stubborn.

If you exit Firefox again, can you:

Create a new Firefox profile

A new profile will have your system-installed plugins (e.g., Flash) and extensions (e.g., security suite toolbars), but no themes, other extensions, or other customizations. It also should have completely fresh settings databases and a fresh cache folder.

With Firefox fully closed, start up in the Profile Manager using the Start menu search box or the run dialog: type or paste the following and press Enter:

firefox.exe -P

That should display a small Profile Manager dialog.

If it visible? If it's off-screen, try pressing the Esc key to cancel it, or Alt+F4.

If it's visible: Don't delete anything here!

Any time you want to switch profiles, exit Firefox and return to this dialog.

Click the Create Profile button, assign a name like 2016May, and skip the option to relocate the profile folder. After creating the profile, select it and start Firefox in that profile.

Does it open on the monitor?

If so, we can advise on how to transfer over your Firefox data from your less functional profile. Here's a general article but it might be a little bit obtuse: Recover important data from an old profile.

When returning to the Profile Manager, you might be tempted to use the Delete Profile button. But... it's a bit too easy to accidentally delete your "real" profile, so I recommend resisting the temptation. If you do want to clean up later, I suggest making a backup of all your profiles first in case something were to go wrong.

Thank you so much for your perseverance! That did it! I am so glad to have my Firefox back again!