I answered your other (similar) question here: http://www.askmehelpdesk.com/retirem...ry-645318.html
The fact that he left no will has no direct bearing on what happens with the 401(k), assuming that he identified a beneficiary (or beneficiaries) for it. If he did not, then since he died intestate the 401(k) is distributed in accordance with the laws of AZ for intestate inheritance. If he has children then the estate will be split between his you and the children.
The fact that the company went bankrupt shouldn't matter, since in fact the 401(k) plan administrator is typically a financial firm such as a bank, insurance company, or investment firm like Fidelity, Vanguard, or Schwab. As I mentioned in the other post, you need to find out who the administrator is and call them.