My close friend has not responded to my texts in a month

My very close friend has not responded to any messages i've sent her the last month. I'm worried that something might have happened to her, or that she perhaps is going through a hard time right now. I've sent her several texts, asking how she is, and if there is anything i can do for her, but i've still gotten no response. Her and I are supposed to attend a festival together this saturday, but I just don't know what to do when I can't seem to get in contact with her... So I was wondering if anyone have any advice for what to do in this situation, if there even is anything I really can do?