Undefined method class::construct() when creating a plugin

In your get_instance() method, you call self::$instance->construct() not self::$instance->__construct(). Also, there’s no reason to call the constructor like that; it will be called when you invoke new self();

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)