At 2 years old 'crying it out' just isn't the answer. There is obviously something wrong for this to change so suddenly. Could you change the ritual a bit more and maybe stay in the room until he felt comfortable? I mean I read a book (or 2 ) to my son before he goes to bed then I sit in there for a bit while he goes to sleep. No big deal. Give it a try -there is obviously something that's making him uncomfortable.