There are so many terrible things that tear families apart. Families that have molestation skeletons in the closet, family members stealing money from each other or borrowing money they never repay, family members fighting over possessions when someone dies... the list can go on and on.
To be honest, your situation isn't that uncommon. Lots of older folks don't pick up the phone. My own mom never calls either. I call her. She's just used to this. I've never argued about it with her, though I've gently teased her. And we live 12 hours away from each other too.
I'm lucky that she is a happy person. We have a caring, close relationship. I'm sorry that you don't feel that same connection with your mom. But it is far different from having the kind of parent who sticks their nose in all of your business, tries to tell you what to do all the time, badmouths you to everyone in the family or social circle, like many women on this site write about far too often.
I hope you will try to just forgive in your heart her shortcomings and pick up the phone and just talk. Quite frankly, your folks sound depressed. You asked for help with your relationship with your mother - not whether or not to dump her from your life. The thought of dumping your parents because they are acting like teens who disappear into their room after school and don't want to talk is beyond sad. Please don't take that advice. Alcoholic parents who siphon money off from you so that you have nothing left for your family? Yes. A dad who threw you away years ago when he left your mom for some gal 2 years older than you? Yes. Parents who beat you senseless for years? Yes. But not because your parents don't pick up the phone and don't play the 20 question game about your life. Being a bit critical is par for the course for some older people - I wonder what we will be like when we are their age (ask our kids years from now if we have escaped that description!)
Where to go from here is just to pick up the phone and start carving out the relationship a little at a time. I can't imagine how bad you will feel if you get a call one day that one of your parents has passed away or is in the hospital in a coma. The guilt feelings will eat you up. It isn't worth going through that over your mom's uninterested, unhappy personality.
If you can just look past her gloomy personality and your dad's lackluster view of life, I think you would be happier and know that you have done right by them, long after they are gone. You will certainly want your own kids to give you a break when you are old, and things are "different" (in their eyes) between you.
All my best,
Dawn