How to change lost password email text using custom plugin wordpress?

The filter for the Message that is sent to reset your password is retrieve_password_message. You use it like this:

add_filter('retrieve_password_message','my_awesome_new_password_reset_email',10,4);

function my_awesome_new_password_reset_email($message, $key, $user_login, $user_data){
   $message = "Hey, you need a new Password? Click here: ".site_url( "wp-login.php?action=rp&key=$key&login=".rawurlencode( $user_login ),'login')."!";
   return $message;
}

$message is the original E-Mail Body, $key is the reset password key, $user_login is the username and $user_data is the WP_User object of the User.
If you return an empty string for $message, no E-Mail will be sent for the “lost password” action.

Happy Coding!