You can’t. Not without enough context.
You are logged in here somehow, and if this login is your Apple ID, then you have both your Apple ID and password saved somewhere. Look in the settings for whatever you’re using to access this website.
Here is what to do: If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
…but that expects you to know some info.
If your credentials are not in your saved settings and saved passwords (used to access this website), then you might regain access to the Apple ID via Apple: Contact Apple for help with Apple ID account security - Apple Support