The email that I registered with is no longer in use how do I log on

Firefox Accounts are currently locked to a single email address and in order to use a different address, you have to create a new account and basically abandon the old one. There's currently no transfer mechanism for the data, so as you add devices to the account, you will be rebuilding its data. <blockquote>Unfortunately there's no way to change or recover the email address associated with a Sync account. You would need to create a new account following the steps described in [[How do I set up Sync on my computer?]]<br>''Source: [[I've lost my Firefox Sync account information - What to do]]''</blockquote> Assuming you have Sync still set up on your Windows 10 installation of Firefox, you can disconnect it from that old Sync account on the Options page, then create a new one with your current address, and synchronize your existing desktop info to it. Then you can add the other devices to the new account. Does that make sense?