What rights do I have to my parents inheritence as an only child?

My parents are in their 70's and their health is not at its best. They live in Tennessee and I live in Ohio as this is where I was able to find employment after I was honorably discharged from the US Navy. Through out the years I have always tried to maintain communications with them by visiting or calling however with my mothers recent series of strokes and broken shoulder my father appears to be in a state of denial and relies on one of his neighbors to keep me informed of my mothers health. My parents are not rich but do have a solid savings with investments average a return of at least $50,000 a year. Their house is worth approximately $400,000. The problem is my father's neighbor has began to interfere with our relationship and I am wondering if I have been cut out of their will and would I be entitled to anything as their only child.