In Windows Explorer (File Explorer), goto "view" and turn on showing of hidden files and file extensions. Then, navigate to "C:\Users\yourusername\AppData\Roaming\Opera Software".
In the "Opera Software" folder, you should see a profile folder for each edition of Opera you're using (or have used). For regular Opera, you should see "Opera Stable", "Opera Next", and "Opera Developer" depending on whether you use(d) the stable version of Opera, Opera Beta, and or Opera Developer. For Opera GX, you should see "Opera GX Stable".
Anyway, if you're using just regular Opera Stable for example, you should only see "Opera Stable". And, if that's all you have, and you goto the URL opera://about in Opera to make sure it's using that folder by checking the "profile" path, then it's likely that your old data is gone for some reason. As to why, I'm not sure.
To investigate more, we'd need more details.
What version of Windows are you using? Is it 64-bit or 32-bit? Also, open up a command prompt, type ver and press enter. Post what that says also.
What Opera were you using and do you have now? Did you have regular Opera or Opera GX? Do you still have the Opera you had before?
You say you now have version 80.0 of Opera. The newest regular Opera is 81.0.4196.37 and the newest Opera GX is 80.0.4170.91. Goto the URL opera://about in Opera and please post the version and what's in the "System" field. That should also tell us whether you're using the 64-bit or 32-bit version of Opera.
Also on the opera://about page, what's it say for the "profile", "cache", and "install" paths? Knowing this will tell us whether you're using a current-user-only install or all-users install or standalone install of Opera.
Also, how did you update Opera? Did it update on its own or did you goto the URL opera://about or opera://update to have Opera check for updates? Or, do you have some program (like a security program) that automatically updates software on Windows for you?
Also, is your user account on Windows an administrator account or a standard user account? And, is the account password-protected?
You lost all your settings too?