What happened to me?

I used to be happy.
Not just happy, overjoyed. Completely, overflowingly, un-containably happy. even I was amazed at how happy I was capable of being. I couldn't ever even remember the last time I'd cried. My life was imperfect but I LOVED it. Relished every challenge, adored everything and everyone, I had endless energy, enthusiasm, patience with people. I was excited for work, to prove myself. I even s smiled when I cried. It wasn't normal, but it was wonderful.
What happened to me? I cry almost every day now. I hate to, almost can't admit, how far I've gone from who I used to be. I don't even feel capable of that kind of happiness anymore. I'm a shadow of that girl. I'm not proud to be me anymore. I'm not excited for the future because I feel destined to fail. I'm ashamed of how often I'm unhappy, and that makes me even more unhappy. I see old friends every day, scared that they'll compare me to the way they used to know me. That they'll see. That they won't want to know me anymore. I can't even put it in words. And that's the clincher. That's who I am now. Unable to put my unorganized, mess of feelings into eloquent words. Ultimate degradation.

I don't know how I got this way.
And I don't know how to get back.