I’m not a lawyer however I’ve been in the financial, banking, lending, and securities industry Door many years.
If there will is not valid, you’ll have to file in the local probate court in the county your father lived at when he died. There, a judge will assign the administrator of his estate. The administrator will be able to interact with the bank and negotiate next steps.
Waiting five years is way too long to but at this point. It’s all spilled milk under the bridge. Contact the bank ASAP and discuss the standing of the loan. Because of the length of time, it’s hard to say what the mortgage status is.
You’ll definitely want to contact an estate attorney to go overall your best options at this point. This all needs to be handled by the administrator of his estate.