I've tried night lights... Music... Books... Nothing is working
She might be afraid of something -- maybe she had a bad dream? You might try talking with her about it. She'll understand more than she can say, of course, but talking clearly about "Mommy is here and will keep you safe." My DS is older, so we do a lot of chasing monsters away or yelling "hey you lions, get out of here!" etc.
It could also be separation anxiety. That kicks off sometime around that age. Anything change recently for her during the day? A new caregiver or other new person in her environment?
You know, my DD randomly went through a week where she eschewed her normal routine and was a big PITA about going to bed. It came and went suddenly. We think it might be teething. I'd say give it another week or so before you really freak out and make big adjustments to her routine or schedule.