Well, obviously it would be helpful to speak with an attorney in your state. Aside from that, you could contact the circuit court in the jurisdiction of your mother's residence and see if a will was filed and/or probated. If it wasn't and you believe there was a will, in most states it is a crime to withhold filing a known will. On the other hand, even if there was a will, it also possible that no assets passed under the will because all of the assers were held in trust, jointly, or by contract (insurance, IRA, etc.), in which case it would be very difficult for you to mount any successful challenge. So, step 1 is check to see if will was filed, and step 2 is probably see an attorney. Good luck.