Went through similar problems with DD, but at a older age. Basically it took both of us working on it. If she mucked around, I would leave and DH would come in so she was not alone. DH came up with the idea of talking about Fairy land and for him to talk about Fairyland she had to lay still, close her eyes and not talk. She would eventually go off to sleep. Counting also worked if she was tired enough, we would start counting fairies, keeping it very slow and monotone. Drove us completely nuts, but it seemed to work and now we do not need to talk about Fairies. Is there something like that you could talk about?

I also found it helps to just continue reading while she played around. It seemed if I tried to get her to stop playing by stopping reading or talking to her, she just played more. If I just ignored her and kept reading in a boring fashion she would eventually stop. She soon learnt that I only read for so long before the light went out, so if she wanted to enjoy the books or have a say in what was read she needed to either sit nicely on my lap or lay in bed.

Experiment with different books, some are better than others for getting them to sleep. Lots of rhythm, rhyme and repetition seem to work well.

She is still not fantastic with going to sleep, but it is so much better than what she was before.