Feeling rejected is one of the most difficult things we humans must endure, and I'm sorry you're going through this. However, please realize that your father's death, while a massive loss in your life, was in no way a rejection of you. You'll always feel the sadness from his absence and wonder what your life would be like if he had lived, but you should never feel unloved by him. What you say to yourself—how you frame your life story—is so incredibly important. Please don't say your father rejected you when he most definitely did not.
As for your stepfather, I don't know the circumstances there. I hope you have a loving mother who's standing by you. As a parent myself, I know how much responsibility it takes to care for children and some people, unfortunately, aren't up to the task. They're too immature, too lazy, too needy, or too irresponsible to handle it. They may be dealing with addiction problems, financial issues, depression, or a midlife crisis. Again, this is not a reflection on you but on your stepdad. You're only 14 so don't take on the burden for the choices adults in your life make.
It would be extremely beneficial for you to talk to a counselor at school. When we talk about heavy issues such as rejection, it lightens our load, and we don't feel so alone and afraid. We get a new and healthier perspective. Reaching out for help is a way to make yourself a priority. You have your whole life ahead of you with so many things to learn and adventures to have. You don't want to stay trapped in this emotional state where you feel unworthy. Take care!