How come my mom keeps rejecting me?

I still don’t know why my mom abandoned me and my dad. She left us when I was 7 or 8 and I’ve grown up without a mother for the past 8 years. I tried to call her but she kept rejecting me and rejecting me. She won’t pick up her phone. My adult siblings (half siblings) have their mom and she is an amazing woman. Why can’t I have that? It isn’t fair. 😔😭😭