If you still have a Firefox icon, just start up Firefox from there. If Firefox somehow got lost or uninstalled, you can download the installer again here:

https://www.mozilla.org/en-US/firefox/fx/#desktop

If your new service requires you to enter connection settings in Firefox, there might be a help article for your ISP, or you could indicate which one it is and a volunteer could try looking it up.

Oops, your question references mobile. If you did a hard reset and need to reinstall Firefox for Android, try the Google Play store. If it says your device is not compatible, a different site for obtaining the installer has been mentioned in other threads here.

I switched my internet serice from Comcast to Verizon. I had been using Firefox and very much want to continue. How can I retrieve my book marks and all my email addresses? Are there any real human beings that I can TALK to about my problem? Are there any 800 numbers that I can employ?

I switched my internet serice from Comcast to Verizon. I had been using Firefox and very much want to continue. How can I retrieve my book marks and all my email addresses? Are there any real human beings that I can TALK to about my problem? Are there any 800 numbers that I can employ?

You may have solved this by now but, if not, Firefox creates personal settings folders under your Windows username. Unless you deleted those folder manually, or uninstalled Firefox and told the uninstaller to remove all personal information, those settings should still be there. If you reinstall Firefox (see link above), the installer should pick up those settings automatically. Hope that works.