Hello, apologies for loosing your notes, but this doesn't sound as Firefox issue but more like an extension/another app issue. Could you add a bit more details on what you mean with notes app?

Dont know what happened. 1 day notes was there then next gone. Doesn't show up anywhere or like it ever existed. I can re8nstall notes app. but cannot find content anywhere.

Hello, where do you keep your notes? Do you use a specific app you can add the name here? Do you use a specific extension? Notes by Firefox is not a supported extension anymore.