How can i get them back into my life?

theres a wonderful girl that im friends with whom i also happen to be in love with. though recent events have caused her to act strangely; she wont answer my texts and whenever i ask her whats wrong in RL she just tilts her head down, smiles, and says "i dont know". all the while im thinking that ive done something horrible to anger her when i havent a clue what that could be. her refusal to talk via text or in the real world is causing me to think she has an extreme contempt for me and honestly its starting to take its toll. ive been feeling extremely lethargic and even getting out of bed has become something of an effort to do. i can feel her absence when i breath, i can feel it in my step, when i eat; every facet of my daily life... and it feels as though its both metaphorically and literally killing me from the inside out... anyway, how can i get her back into my life? if not as a lover then as a friend =/