What's wrong with my best friend?

My best friend is Lydia, and we've been best friends since kindergarten. I moved in October 2008 350 miles away. In the summer and during school breaks we saw eachother often and always had a great time. For her birthday two years ago, she got a laptop - the first computer in their house. And she had to share her cell phone with her dad who took it to work usually, so I knew I couldn't call/text her much and counted on her being on the computer often so we could communicate. She never goes on the computer, even though her parents have their own computer so she doesn't have to share. And she and her parents recently all got new phones. For the past three weeks or so, I've tried texting her at least once every two days and calling every 4-5 days. She NEVER answers calls or voicemails and doesn't reply to any of my text messages. And she never replies to my emails, either. We used to write letters, but she always writes short little messages with the same info - "Sorry I never call you or text you; I've been busy," and maybe one little thing going on with her, even though I go really in depth in my letters. The last letter I sent her was sent about 2 weeks ago and she STILL hasn't replied. It takes exactly three days for our letters to get to each other. So, does anyone have any suggestions or ideas?