C.S.
My 2 year old did the exact same thing at 18 months. You have to let them cry it out. What I did was go in there every few minutes a few times then put more time between visits to the crib. keep doing that until she's asleep. I also put a clock radio in the room that has a setting that only plays for an hour. She was usually asleep in that time. I kept it really low on an easy listening station. It was like the room was to quiet and it scared her. This not sleeping thing came totally out of the blue for me but I knew not to pick her up and take her in another room, she was the 4th and I'd made that mistake enough times to know not to do it again. It's just a stage you have to train the baby to get past.