I Need Help With A Good Friend

I left a message on another board but I was reading this one and maybe this is were i should of put my story. I have a friend who has been on cocaine for nine month now. she has been on it before. But i didnt know her than. She is a wonderful person and who is always giving a helping hand to anyone but will not ask for help herself. I am at my wits end. I dont know what to do anymore. I have tried being nice and mean I offered to go to classes with her. She will call me when she has taken alot and than I lay a wake and worry is she going to make it though the night. When I tell her the truth she wouldnt talk to me for 3 or 4 days and that drives me nuts. I see her almost everyday we work together. Its like riding a roller coaster up and down and around all kinds of corners. I dont know what to do I just want to help. She keeps saying she wants help but than when we get it together she doesnt take it. Anyone have any ideals. She use every day and alot of it. some days every half and hour. Do I turn my back or do i keep on pushing. I dont want to give up!!
JD3, keep the relationship going. talking to her about cleaning up while she under the influence is useless. it will have to be while she is sober. the best time to talk to her is unfortunatley after she screws up big time -- which she will eventually do. there is a period of remorse, guilt and shame that usually sets in -- many times it doesn't really last long. that's when a chat might do some good. and she will need a friend. the denial is so strong with addicts and the memory of the pain is short. at those times of loss sometimes they can see a glimmer of the fact that their life is unmanageable and they need help -- that they can't do it alone.