Missing a friend so badly.

I am 17 years old. I had a very beautiful friendship. She was my bestest friend. But all of sudden she started departing herself. When i asked her the reasons she told me that i never treated her as a bestfriend, i didnt give her such importance. Somehow i felt guilty and started apologizing her. I cried and literally begged to her that donot end our friendship donot change your behaviour but she started ignoring me. From march 2018 to december 2018 i kept going her home i kept meeting her but she neve gave me that response. I kept pleasing her. I kept texting her that i misd you so much. But her response was nil. I am a pre medical student and i cannkt even study. I and she are in the same college whenevwr i see her laughing and chilling with other people and she ignores me this hurts me so much. I did all the possible things that can make her happy. But she did not become same. She is having birthday in february can u guys tell me either i sould give her surprise or not ? Can you guys tell me how can i overcome with my depression? Can you guys tell me how can i overcome with all the tears? 💔