Friends to strangers (short version of the story)

i meet my old best friend 2013 freshmen year of college. I'm not sure why we stop being friends. She stop talking to me for a couple of days and I called her. She thought I was mad at her and I told her no. After that we stop talking completely. 2016 I reach out to her trying to build our friendship back. She didn't respond. 2017, she called me random. The next day I text her and the conversation was very dry. She acts like I was bothering her. I miss my best friend so much. I always wonder why she did not try to reach out. At this point, I feel like its not point of trying to reach out but I'm not sure.