A close female friend of mine is mad and in a bad mood. What should I do?

I don't believe she's mad at me. I haven't done anything to make her mad. She's mad at something going on in her life and it's bugging me. I want her to talk to me about it and get it off of her chest but I'm not sure how to go about doing this. We text all the time and I can't physically see her because we don't live close to each other. She' doesn't like to talk on the phone so we text all the time. She's not really texting me and I don't want to seem like an annoyance when I'm just trying to help. What are some thing that I could say to her to maybe get her to open up or just talk to me in general about the situation? Thanks!