Sorry to hear about this problem.

Sometimes add-ons are a factor when you have problems with the user interface.

Plugins

Check whether you have any "global" plugins that have an effect outside the web page, as opposed to "player" type plugins. For these plugins, if they are set to "Ask to Activate", change them to either "Always Activate" (if they seem useful) or "Never Activate" (if they seem unnecessary).

Open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Then you can adjust the permissions setting for each one.

Extensions

To see whether one of your extensions might be involved, could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

I had same problem. Running in safe mode with all add-ons disabled worked fine. So I disabled one add-on at a time until I found the culprit:

Tab Utilities Lite

Disabled this add-on and browser worked fine. Looks like add-on needs an update for new version of Firefox.

Try to open a new window to see if the location/address bar works in that new window.

Thanks all of you, but it didn't work.

If the problem is related add ons, I might uninstall and re install Firefox

Uninstalling and re-installing Firefox won't touch your addons, so if that is where your problem lies it will be a waste of time.

Try the Firefox SafeMode as advised in the first response to do a little troubleshooting.

Or do a Reset of Firefox. https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems

If Firefox Safe Mode didn't help for you then try a clean reinstall.

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

• Download the full Firefox installer and save the file to the desktop
  https://www.mozilla.org/en-US/firefox/all.html

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then also create a new profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

It did work thanks everyone for your time. I got Firefox back!

You're welcome.

Can you confirm what did work?

It can help other with the same issue that read this thread.

Sorry I forgot to tell. I reseted Firefox, acordding the instructions in te link: https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems

Thanks everyone