Do I have a case? My brothers swindled me out of my inheritance.

My mother passed away first and willed everything to my father: home, investments, bank accounts. A week after my mother dies, my father is admitted to the hospital. My older brother becomes power of attorney and talks dad into cutting me out. My dad is medicated at the time and has the onset of Alzheimer’s. I have an audio of this conversation where my dad is confused and insists that everything should be split equally 3 ways between each brother. My brother tells him that the beneficiary has to be changed on his investments, or the bank will keep the money. The investment form is changed through the bank leaving me 5% and the other 2 brothers splitting the remainder of almost $200,000. After my father passes away, my brother becomes the executer of the estate. I am just finding out this information and not sure what to do. My father passed away earlier this year and the investments have already been disbursed. Is there a time period that I have to do anything?