<human>: Hello Reddit,

From the title, I'm sure most of you are reading this thinking "what the fuck is this guy talking about". Well, I met this amazing girl that an old high school friend reminded me about. I've seen her a couple times in the past year or two, and she's absolutely beautiful. I started talking to her over Facebook for the past several weeks, and we exchanged numbers and eventually started talking on the phone, some of them for hours at a time. I've learned she has some of the same exact likes I do, when it comes to food, music, traveling, everything. Her personality is addicting and that's why it's been so easy to talk to her for so long every other day or two for the past two weeks. I know this seems like infatuation, and it probably is. But a day or two ago, she just stopped talking to me suddenly. We had gone from constant interaction and planning on an upcoming date, even her calling me just to let me know how her day was to just that - nothing. I asked her what was wrong or if I did something, and she told me she just wanted to be alone. I asked her if she wanted me to stop talking to her for good and she said she didn't know. What bothers me is that this girl that I've been falling for hard went from someone bubbly and excited to talk to me, to someone that seems like we haven't talked a single time before. 
What I'm asking is...what to do here. Obviously I need to refrain from talking to her unless she messages me, but all I do is think about her and why/how it became like this. From what I know she hasn't dated someone in almost a year so it's not a previous ex she's trying to get over. It's just so weird and crushing. Someone that talked to me like a best friend and even called me some pet names, to zero communication.

Reddit, what would you say I do? She's an amazing girl, in every aspect. But I don't want to feel like this anymore.

Can you summarize the given text in a few sentences?
<bot>: Talked to a girl I've been starting to fall hard for for 2 weeks, and then she randomly stops talking to me out of the blue. What should I do?