My friends make fun of me

I am a student and I can’t focus on my studies cuz my “friends” call me words like the n word even though I’m not that And make funny comments of my appearance.

I had tried to tell them to stop many times but I won’t work.I have told my teachers in the past but learned my lesson not to because it’ll make things worse.I don’t wanna hurt them.I don’t know what to do and decided to get some advice on the internet.Just please be friendly