Manasseh is very different from his father Hezekiah. Manasseh is openly rebellious against the God of Israel and pursues all kinds of other gods. He even sacrifices his own sons to another god. He does this in the valley of Ben-Hinnom. In the New Testament, this place is called Gehenna, which is also a way of referring to Hell. Hezekiah returns to God when God warns him, but for Manasseh, it takes being taken into captivity for him to see the error of his ways.
God uses different methods to get through to those he loves. For those more open to God, a simple reminder in a Bible reading may be all that is needed. For others, it might require a difficult conversation. Like Manasseh, some require terrible circumstances to realize their need to change direction.