I have a 26 month old who has always slept through the night (unless poorly), but has suddenly started waking and becoming hysterical and uncontrollable.
We have a very good bedtime routine, which we have used since birth more or less. Supper, bath, story, into cot, a quiet song, leave the room. DS then chats to himself happily, talks about his day to his toys, sings to himself or whatever, until he falls asleep. He always just lies down, shuts his eyes and tries to go to sleep.
The last few nights when he has woken (or when he hasn't gone to sleep) he starts crying, then says he "wants to get out" (of his cot), asks for mummy or daddy to come back etc. This continues until he is virtually hysterical. No amount of returning, talking to him, patting his back etc etc makes any difference. there is no way to comfort him - he is beyond control or comfort. This can go on for hours :-(. The last two times I have got him up (kicking and screaming and saying no) taken him downstairs or into our room, waited for him to pull himself together (usually by employing some distraction), let him play and wind down for 20-30 mins, then taken him back and gone through the bedtime story night-night routine again. He has gone back to sleep.
The trouble is I don't think this will help solve the problem, if anything I am perhaps making it worse, by him not falling back to sleep by himself. I've always had a strict rule about night time being night time and we have never left the bedroom, or played or put the light on etc. And I belive this is why we have (until now) had such an easy time with DS at bedtime and with him always sleeping right through the night.
Because he is utterly hysterical (as opposed to simply crying) I do not feel I can leave him. But I have no idea how to deal with this and put it right :-((.