How can I get my inspiration back to write my story?

Currently I’m in process of writing my story. At first I was full of energy and enthusiasm. In other word, I was hopeful that my story would be as good as I had speculated. But now all my enthusiasm has mysteriously disappeared. I don’t have any more new ideas. I feel as if my story has come to the dead end. What’s worse, I have a feeling that there’s something wrong with my story (it’s suck, to be exact). In short, I feel totally uninspired and skeptical about my progress! I know that feeling is horrible, but I really don’t know how to get over it. Is it because I’m skeptical about my ability or my story is that bad? Do anyone here know how I can get my inspiration back?