I don’t know my password

See if you can recover the ID/password. Use every email address you can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

If you forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage            

Apple ID – Forgot Password            

When your phone is not able to register your account with your phone number, it just gets registered to iMessage and FaceTime with your Apple ID. So, you can ask your friends and relatives you got connected through iMessage and FaceTime, if they can see your Apple ID.

Additionally, if you're using a Mac or PC to connect your Apple ID through iTunes or Apple-related websites, you can check if your login session is still alive, so you will be able to see your Apple ID.

You can also check iForgot.Apple.com website and check the "If you forgot your Apple ID" section. If it's still no relevant, so, consider your Apple ID as a door and the password as a key. You won't be able to access your data, if you're missing your door and the key to your home.

Are they not the credentials that you used to login to site and post ??

If not, you’ll need to start at https://iforgot.apple.com/

Got watch from some one and they don’t remember information

See my post above. See if they can recover the ID and password.