The opening sentences to your story should accomplish three things:
Can you let that hook go, moving forward to finish the story?
Can you let that hook go, and rewrite a new opening?
When I find myself in this uncomfortable spot, I put aside my writing and browse my bookshelf, reading the opening lines of many stories, and that is where I find myself inspired all over again. I can breathe in that space of great literary minds. I'll get it right, if not right now, then later.