What should i do if someone starts hating me without any reason?

Maybe u done something wrong and didn't realized it? First try to find out why hes mad and find a way to fix it, i mean if he is a friend i don't think he got upset over the hard time and nice chat's so must be something else, if u don't find out why he/she is mad/upset u wont be able to do anything and your friendship will be ruined but don't give up !!!!!!!!!!! try to overcome the situation as much as you can, maybe u can ask his friends or something? maybe they will be able to help you? I don't now anything else so do your best........