You've asked this repeatedly. Again, contact the 401k program administrator at the employer. If there actually IS a 401K account there in his name, he would have been getting account statements since he left that employer. How do you know you're the beneficiary since you seem to have no documentation that such an account exists?

Check his pay stubs, W2 forms, Tax returns.

He should have been getting 401k Earnings Reports, yearly for tax purposes.

If he was retired he may not have one anymore. Many of us rolled ours to a IRA so old employers have nothing to do with it. If you know what company has his account you can contract them. Make sure you talk to your accountant about taxes on withdrawals and RMD since you can be hit with a 50% penalty plus taxes so lose over 75% if you do it wrong.

I don't know if you called them on the phone or went into the Human Resources office. If you just spoke to them on the phone, I would go to the office. There is no reason for them to be jerking you around as they can look it up.

just contact the plan trustee. Forget about the damn employer, THEY DONT HAVE THE LOOT. They're really not ALLOWED to have the loot. That is the LAW.

CONTACT HIS EMPLOYER and quit asking random strangers online who can do absolutely NOTHING for you.