Solution:
By default, WordPress uses gravatar service to display user’s profile picture. Users profile picture is based on your email address. If users do not have a gravatar account then your profile picture will be replaced with a default image placeholder which is called “Mystery Man”. this is how user can set their gravatar picture.
- Visit Gravatar website.
- Sign in to Gravatar with your WordPress.com account. If you don’t have a WordPress.com account then you need to create one.
- Upload your avatar (profile picture).