How do you get power of estate?

The documents you listed are only effective while your father was living. The moment he passed away all of the documents became void. Someone filed  an application for probate  and was appointed executor, if there was a will, or administrator, if there was not a will. Once appointed  as executor, the person has the ability to handle all  financial matters of your father's estate. Since your power to handle your father's affairs ended at his death, the court was able to appoint someone else to handle his affairs after death. All probate  matters are of public record,so you will need to go to the county court where your father was living when he died and look at the probate records  to see who was appointed  executor. Since I do not practice in New Jersey, I am giving you the law that applies  generally, so I recommend you asked someone who practices law in New Jersey  for specifics on how New Jersey handles  probate.