Wordpress: Change profile picture wihout plugin and gravatar

1. Step 1: go to wp-content/themes/yourtheme/functions.php
2. write: 

        add_filter( 'get_avatar', 'ChangeAdminProfileIfNot', 10, 5 );

        function ChangeAdminProfileIfNot( $avatar = '', $id_or_email, $size = 96, $default = '', $alt = '' ) {

            if( "user_has_uploaded_a_local_avatar") {

            

                $avatar = "<img src='your image path' class='avatar avatar-{$size} photo' height='{$size}' width='{$size}'";

                

            

            }

            return $avatar;

        }

Note: 

user_has_uploaded_a_local_avatar

This will check user or admin have profile picture

If you want to change profile picture only for admin 

then write:

        add_filter( 'get_avatar', 'ChangeAdminProfileIfNot', 10, 5 );

        function ChangeAdminProfileIfNot( $avatar = '', $id_or_email, $size = 96, $default = '', $alt = '' ) {

            if( "user_has_uploaded_a_local_avatar"  && strpos($avatar, '524839ea4d48eb11da1325dc1bfccc14') !== FALSE) {

            

                $avatar = "<img src='new image path' class='avatar avatar-{$size} photo' height='{$size}' width='{$size}'";

                

            

            }

            return $avatar;

        }

524839ea4d48eb11da1325dc1bfccc14 
this is my admin image id. find your image id. You can check your image id using inspect element.