How should I handle this communication situation?

My girlfriend moved to the other side of the country about two months ago, for a job. She did all right with staying in touch for a while, and has always maintained that she wants for the two of us to stay together. But, eventually, she mysteriously stopped talking to me. With the advice of some close friends, I decided to hold off from talking to her until she talks to me, to give her some space. A month has ped now, and it doesn't seem that she will ever get in touch. It is by far the longest we have ever gone without speaking to one another in the history of our one-year relationship, and I'm quite worried that something is wrong. The lapse in communication is unacceptable to me, as she promised from the beginning that we would make this work, and frequent communication was a condition of that. I feel the need to contact her myself now and decide whether or not this will work out, but I'm afraid that with the frustration I feel toward her not communicating with me will cause me to be angry in approaching her. Basically, I feel like I could be wasting my time waiting around for her if she doesn't want to be with me anymore, and I feel an urge to get to the bottom of it so I can get past all of it. Does anyone have some suggestions regarding a way to approach her nicely and respectfully about this, without being hostile or coming off that way?