How to see a copy of my grandfathers will?

My granddad passed away in 2014 my mom clean up the house the next day, I think she found the will, I know he had told me that all of his things, land ,money ,multiple bank accounts would be mine, she says they ain't, and that she has got it took care of , but won't show me the will, I can't seem to get a copy, my grandmother is still alive, but has dementia and my mother has took over power if attorney, most everything in his will should go to my grandmother till her passing then he said it would come to me... can she change that with my grandmother not being in her right state of mind? Is there anything I can do to get a copy of that will? And no it has not been probated even though it has been about 4 yrs since his passing, what can i do? Or does she just hid the will and she gets everything just because she is his daughter?