If no one can find my brother who was beneficiary on a life insurance policy from my father, can I claim the money?

I am so sorry for your loss and for the situation as it now stands.  Unfortunatley, you can not collect on the insurance policy because you are not the named beneficiary.  You would have to prove that your brother was deceased or have him declared legally dead.  And even then, the policy itself will provide for a contingent beneficiary, which is generally the estate.  Seek help from an attorney who can determine what the rights of the estate are under the policy.  Good luck.