Should i ignore my crush back?? he has been ignoring me.?

We used too walk 2 gether after class. flirt with each other like crazy. we used touch alot and laugh and smile but lately he has been ignoring me. we dont walk together no more we dont flirt no more even if i try he doesnt let me, he just says hey! all serious. he ignores me everytime i say hi to him. i am just sad and heartbroken because he acted like he liked me and not no more. and i really like him but idk what to do now ijust wish he wasnt ignoring me cuz it hurts me a lot :(