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}

Is it a Windows 10 laptop?

I don't know whether this might be the problem on yours, but when I installed Snap Camera recently (so I could be a potato on Zoom calls), it clobbered the VC Runtime files. I didn't realize this was why Firefox wasn't working until I re-ran the Firefox installer from https://www.mozilla.org/firefox/all/#product-desktop-release

After that informed me of a VC Runtime problem, I reinstalled the latest 32-bit (x86) and and 64-bit (x64) files from Microsoft, allowed Windows to restart, and all was well again: https://support.microsoft.com/en-us/topic/the-latest-supported-visual-c-downloads-2647da03-1eea-4433-9aff-95f26a218cc0