Hi, I need more info about this issue : have you tried to open a website with another browser? What's the status of your Internet access?

What's your computer system and Firefox version?

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Windows 10 and I downloaded the latest version of firefox. I'm using windows defender firewall and removed and added firefox as trusted. Firefox wont even open its options.

ADSL 10mb/s internet and other browsers work

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

Restarted in safe mode with networking and no change. Websites and options won't open. Uninstalled firefox deleted all firefox files left, reinstalled firefox again and still no joy.

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.