Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you.

Should have mentiond I tried the de-install/install suggestion before but via the Settings/Apps page. Just to be sure I did it this time deleting the Firefox folders manually.

Still no joy, bookmarks toolbar still missing. It shows for a second or so on start up and then vanishes.

Thanks though!

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller (for more info, see this alternate TDSSKiller download page)
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Kaspersky is used in combination with Malaware, Spybot & ADWCleaner. Pretty sure that won't be a prob. I'll scan stuff in a second, doubt it'll bring up anything.

Thanks though.

Is there an empty Bookmarks Toolbar, or is the Bookmarks Toolbar completely missing?

For an empty bar, use the "Restore Defaults" button in the Customize screen. See: Customize Firefox controls, buttons and toolbars.

The xulstore.json file

You didn't mention whether you tried a Firefox refresh. Assuming not:

Sometimes the settings file that stores various user interface dimensions becomes corrupted with nonsensical values. You can rename the file and have Firefox rebuild it. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > 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, on the Profile Folder row, click the "Open 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 > Exit
• (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?

That mini-reset will hide the bookmarks toolbar. You can use one of these methods to show the toolbar list and select it there:

• right-click (on Mac Ctrl+click) a blank spot on the tab bar (or the "+" button)
• (menu bar) View > Toolbars
  On Windows, tap the Alt key to activate the menu bar temporarily.
• in Customize mode > Toolbars button (see: Customize Firefox controls, buttons and toolbars)

To turn on the Bookmarks Toolbar, click it on the list.

Restoring a closed window

In response to the other issue you mentioned: Firefox remembers up to 3 closed windows by default (you can increase this if you like). There is an entry on the History menu to restore them, either:

• Library toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

If you don't normally display the classic menu bar (File, Edit, View...) you can display it temporarily by tapping the Alt key or F10.

Note: there's also a History Menu button available on the Customize screen if you don't like using the Library button.

The Bookmarks Toolbar is completely missing, allthough, if I start Firefox after a complete exit it does show for a second fully filled with what I had in there.

Thank you for the note about restoring a closed window, did not know that and seems to be very helpfull for future use. Cheers!

I'll try the xulstore.json solution in a moment and let you know. Thanks!

Did the xulstore.json thing. Same behaviour. When I start Firefox the Bookmarks Toolbar is there for a second or so, then disappears.

Hi BorkBork, have you ever created or downloaded a userChrome.css file? It's a style rule file that can be used to customize Firefox's toolbar area. To check for that:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > 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, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Do you see a folder here named chrome?

If not, we're done with this theory.

If so, double-click into the chrome folder and see whether you have a userChrome.css file.

Note that by default, Windows hides the .css file extension (along with .txt and many other extensions). You can set Windows to show all file extensions using the steps in this article:

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

I have that Chrome folder. There's a userChrome-example.css and a userContent-example.css file in there. Both are almost 8 years old though.

The -example files are not active -- Firefox doesn't load those -- so you can ignore them.

I think it has to be something in your profile, but what else could it be?

Could it be an unwanted side effect of an extension? You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions.

Then cast a critical eye over the list on the right side. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove).

Any improvement?

Well, all of them are there by choice and have been there quite a while. I had this Firefox synced with two other PC's. Same addons, they work fine, except had to turn off sync bookmarks on them 'cause I would end up with an empty Bookmarks Toolbar on those pc's.

I disabled most if not all. No effect.

Did you check "History -> Recently Closed Windows" to see if you could recover your main window?

You need to close that 'pop-up' type window and open a new regular window. A pop-up windows behaves differently then a regular window and websites can disable features like displaying toolbars. If that doesn't work the delete sessionstore.jsonlz4 in the profile folder with Firefox closed.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Make it a habit and use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar to avoid surprises with unnoticed pop-up windows.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit

Checked but main windows is not there in my history of recently closed windows.

At this point I'm thinking of deleting Firefox and my profile and installing a fresh one and let it sync with my other PC's. Should get most of the stuff back no ?

I don't know what Sync will bring you. You can test without deleting anything:

Copy A Bookmark Backup to Your Desktop

This is for easier access in a new profile. The files are stored in a bookmarkbackups folder in your profile (same steps to locate as when you were tracking down the chrome folder).

New Profile Test

This takes about 3 minutes, plus the time to test synchronization and the toolbar.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like July2018, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. Please ignore any tabs enticing you to activate extensions found on your system so we can get a clean test.

Does the Bookmarks Toolbar appear persistently?

You can restore the backup from your desktop (use the "Choose File" item on the Restore menu): Restore bookmarks from backup or move them to another computer.

Better? Worse?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.

I went ahead before I received the above answer but luckily things went rather ok.

Deleted Firefox and my firefox profile. Reinstalled from scratch, enabled the bookmarks toolbar, logged in to Sync and let it do its work.

The theming got reset on both PC's and some addons did not sync over to the new installation. But best thing is I got my Bookmarks toolbar back and filled.

I'll mark this as solved so others might use Sync as a last resort. Thanks all!