I created an account, had been playing a campaign for a few months. Recently I cleared my browsers data and cache. I just logged back in for the campaign session and it says I have no characters or campaign. However the other players can still see my characters. I am on the right account, I checked my email verification and it's the right email that I used to sign up. And the same username that the other players can see. But in my account it shows I have no characters or campaigns

You logged in using an alt account, it happens all the time. I know, I know, I read your post. You think you’re in the right account, but it’s not. Log out and log back in under the other login methods (Apple, Google, Wizards), and see if you can find the right login method. Make sure not to use the “hide my email” function if it prompts you.