This Apple article has instructions for what to do if you have forgotten your Apple account password, or the system does not recognize the one you remember —> If you forgot your Apple Account password - Apple Support
or go directly to this link —> http://iforgot.apple.com/
If you don't receive your verification or reset email, read this Apple Support article: If you didn’t receive your verification or reset email - Apple Support
"When you make certain updates to your Apple ID, we’ll send you an email to help you complete the update. For example, you might have reset your password, reset your security questions, or added a new email address to your account." Also check your junk mail.
Apple stopped using security questions several years ago and does not actively support them. If you have to resort to security questions you will instead have to contact Apple and see if they will help you with account recovery and setting up two factor authentication instead.
This page has telephone numbers for contacting Apple for support and service ➞ Contact Apple Support - Apple Support
If you are signed into this forum using the same Apple Account then your browser may be configured to automatically enter your password. You should be able to view stored passwords in your browser's preferences/settings.
You say this was a long time ago so you may wish to realize the account may be permanently gone already: Legal - iCloud - Apple
VII. B "In addition, Apple may terminate your Account upon 30 days’ prior notice via email to the address associated with your Account if (a) your Account has been inactive for one (1) year; or (b) there is a general discontinuance of the Service or any part thereof."