Thanks for the post rafadizeo. The get_avatar code line which caused my issues in the function.php file read like:
function get_avatar_url( $id_or_email, $args = null ) {
$args = get_avatar_data( $id_or_email, $args );
return $args['url'];
}
and I changed to:
/*function get_avatar_url( $id_or_email, $args = null ) {
$args = get_avatar_data( $id_or_email, $args );
return $args['url'];
}*/
Everything seems to working ok since the change, and I can access my website again. Happy days 🙂