INHERITANCE Brother Asking For Power Of Attorney After Father Passed

My brother is asking for my signature for power of attorney but I don't know where my name is in this land. My father passed away and after that he has been forcing me to sign the power of attorney. How do I get hold of the certificates or will if he does not give it. I don't know if there is a will but he is only asking for my signature. How do I find out what is in my name if my brother does not give any documents. He is not giving any documents and I don't know about my dads lands and properties. How do I get the certificates or find out if there is a will.