Hello,

First reboot your computer and try open again, case doesn't start, try the below ideas:

Try Start in Safe Mode:

• Firefox in safe mode

There is a help article with some tips, see if one help you:

• Firefox won't start

We need the maximum information that you can give us

• Create a screenshot of the problem

the similar question:

• /questions/985850

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

I cant uninstall the previous Firefox in my laptop. it always shows a window saying "firefox must be closed first".. how to close firefox if its not even open? i need help.

i dont know how to close the firefox so that i can open or download a new one

Sometimes when FF is closing, not all of it shuts down properly. On Windows, start the Task Manager (Other systems may have different names). Select Applications (list of what user programs are running). If you see Firefox listed, try to shut it down normally. If it does not shut down, then on the Task Manager right click FF, and select End Task. However, if FF still does not shut down, or FF is not listed as running; on the Task Manager, select Processes. Look down the list for Firefox. Right click and select End Task. If this problem keeps coming up, ask for more help.