My friend is mad at me.what should I do?!!!?

Okay my friend and I planned that we would do stuff Saturday night(which was last night) like watch movie play cards and make food.But she knows that I work all day Saturday and told her that I might get out late like around 9:30 pm...I called her and she's like you know I don't want to make plans anymore.they never come true and it's too late.I've been looking forward to this and now everything is ruined.and she starts saying like only call me when u need me but don't expect me to make plans anymore.urghhh I told her before that I work all day and I might get out late.and I did my best to get out early.and there were times I made plans and she couldn't do it bec she was having a bad day or something and I always understood.I don't know what to do.I love her bec she's my best friend and I don't want her thinking like that.:/