We had a similar problem for a while - our now 3 year old sept through from 4 weeks old, then suddenly at about 2 she developed sleepless nights (which was a mega shock to us!). We introduced a star chart, 15 stars to a big treat, stars given for all sorts, but 1 star given for every night she did not wake mummy and daddy up - we were AMAZED how quickly she stopped - we still use the star charts and they still work - 12 months on. We also had her treated by a homiopath friend. At the time she was screaming for up to 2 hours each night when she was put to bed, and we were at the end of our tethers. Also, she had had about 5 sleep broken nights at the time, and had not napped during the day for over 6 months. We gave her the tablet and within 10 minutes she was asleep on the floor on the lounge. And from that day we have never had screaming the like of which we saw pre-treatment. Good luck mummy, I know it seems unsolvable, but there will be a way of getting your daughter to sleep through!