Susan: try going to https://reg.franzis.de/en/login … You’ll probably need to use the “forgot password” link, unless you happen to remember your Franzis account password.
Once you get logged in, you should see the Franzis products you’ve registered. There should be a button on each one to have Franzis resend your registration code to your email. And do check your spam folder if you don’t get it in your inbox. And you can keep clicking the button to get it to resend again, if you need to.
Recent Franzis products use a different registration system, and won’t appear on that page.