Can a person really change?

We wonder if people who have been in some form of bondage (such as drugs or alcohol) for years will ever be able to change. When will they stop? when will they stop and say i need God? Sometimes we figure they are just going to die that way. Manasseh was such a man who was really messed up. But God. Thank God for when He butts in! Can the old come off and the direction be reversed? For Manasseh the most wicked king Judah had it happened. Can we have that too?