I changed my xfinity e-mail password and now I'm locked out of my apple e-mail. It does not accept either my old or my new password now.

Your Apple ID password or the password for your email address that you use for your Apple ID?

For the Apple ID password, if you know the current password.

 Apple ID Password Change.   -   

 What to do after you change your Apple ID or password - Apple Support  -   I suggest doing this before you change your Apple ID or password.      

If you forgot the Apple ID (iCloud) 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  *      

For the email address password, go to the email provider's web site, access your account, and in the login area, there should be a forgot password option.