Hello nickyfrance, have you tried restarting your operating system to see if firefox works fine?

You can also try this. It's not the regular way though. 1. Go to computer. 2. 2x Click Local disk :C. 3. 2x Click Program Files (x86). 4. Locate and find ALL Mozilla files and delete.

Same with Mozilla Maintenance. 1. Go to Control Panel. Open Programs. 2. Uninstall Firefox. It will, not be able to but it will ask to remove all of its features. 3.Click yes.

Do the same for Mozilla Maintenance. DONE!

@nickyfrance

You can also try this. It's not the regular way though. 1. Go to computer. 2. 2x Click Local disk :C. 3. 2x Click Program Files (x86). 4. Locate and find ALL Mozilla files and delete. Same with Mozilla Maintenance. 1. Go to Control Panel. Open Programs. 2. Uninstall Firefox. It will, not be able to but it will ask to remove all of its features. 3.Click yes. Do the same for Mozilla Maintenance. DONE!

These steps will erase Firefox from your computer and any bookmarks/personal saved data you had in Firefox.

@benjamindmanford: Please don't suggest doing anything to Mozilla files ESPECIALLY deleting. This is not recommended to users at all since they might delete an important system file and render their system unusable.

As for your issue with Firefox, it may be running in the background. Read How to close Firefox when it says it's running.

Got that Moses

So what should I try then Moses? I really need a solution :(

Nickyfrance As for your issue with Firefox, it may be running in the background. Read How to close Firefox when it says it's running.

Previous post had it too.

It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating

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

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 27: http://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 all profile folders will be removed and you lose personal data like bookmarks and passwords from profiles of 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 that "remove personal data" is NOT selected when you uninstall Firefox.

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

I have done that Moses - useful tip! I have now uninstalled Firefox and reinstalled it but it is still not working. What can I do now?

@cor-el I have done all those things and now have a new version of Firefox but I still can't open it!

Actually, that's not strictly true - I have done a clean reinstall but I have not been able to do anything with my firewall settings as I don't know how :(

nickyfrance:

When was the last time you updated you pc?? Also try updating your pc and try starting firefox. If it doesn't work, try reinstalling once again.

What do you mean 'updated' my PC?

Installed windows updates??

It updates automatically.

Ok try and boot into safe mode. Once you are there, try uninstalling mozilla and boot back into normal mode and install mozilla from there and lets see what happen ok.

How do I get into safe mode? My last solution was to pull the plug on the computer and then it offers me the safe mode option when restarting. I assume there's a better way?

Here is a useful link to help you start with

http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7

Which firewall do you have?

Is it covered in one of the knowledge base articles?

• https://support.mozilla.org/kb/Firewalls
• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating

I have now added Firefox to the list of permitted programs (it wasn't in the list) but it still doesn't work.

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes