Toddler sleeping troubles!!

Hi my niece is 2 years old and is having an awful time falling asleep. We have always had a schedule for her: dinner, bath time, read some book, then go to bed. She seems to have her nights and days mixed up. We also don't let her sleep during the day hoping that it will tire her out enough to go to bed at a reasonable time. I guess I'm asking is there anything you can suggest that I can give her to help her fall asleep and stay asleep. Thanks for the help!