If those notes were created by an extension then you need to contact the developer for support. An extension would store its data in the browser-extension-data folder in the profile folder.

Do you at least still have the extension? If not then check if you have an "Old Firefox Data" folder on the desktop in case Firefox has been refreshed and created a new profile.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thank you very much for responding, I appreciate it. I hadn't realised that Notes was not 'officially' part of Firefox. Turns out it is a Firefox Test Pilot addon. I contacted them via the drop-down menu at the notes column, but only got a form to fill in with feedback info, which will clearly go nowhere. It is not mentioned in the list of extensions/addons in the profile page. No old Firefox data folder that I have found.

I am trying to find a way to contact the Test Pilot team. Somehow I followed a link to Github, and posted there, but I'm a bit clueless about all this. I'm amazed at how old that mozillazine information is, don't they ever update it?

I will work on this on the weekend when I have more time to try to figure it all out. Never tried using a new profile, and I thought I had my profile data backed up, but it's all very complicated for a non-tech person.