Here are a few ideas that didn't help my four year old stay in his room and sleep but that might help your daughter :-)
-Make a trip to the store to pick out a sleeping friend like a stuffed animal or blanket. It will make your daughter feel she has more control
-Let your daughter sleep with a photo of you or someone else they feel safe with.
-Make a ritual bedtime routine and don't deviate from it. Like brush teeth, go potty, read a book, (prayers?), then daughter goes to sleep and mom has adult time
-Tell her that she doesn't have to go to sleep, just stay in her room through the night. Explain that you feel tired and want your rest for tomorrow, but she can do what she wishes as long as she stays in her room. When the next day arrives, get her up at her normal time. she will be cranky, but she may get that going to sleep is a privilege, not a punishment. It works better if the night you implement this you have something planned the next day that she would enjoy. She might be too young for this technique, I am not sure.
-When she awakes, go to her instead. Lay with her in her bed or on the floor. When she is asleep you can slip back to your room. This way she knows you aren't giving in. THis worked for me, until I was so exhuasted from getting up and down (I have three kids)I would sleep more soundly. My son would awake, not make a sound and slip into my bed. I never even knew he was next to me until the next morning!
-Let her pick out a flashlight to make her feel safe. The drawback: 4 year olds like to play with them instead of sleeping. But if you do this when something fun is planned the next day, and she oversleeps, she might feel it is important to sleep but feel safe if she awakes with a flashlight.
-Give her something that smells like you. Like a shirt you have had for a long time. I have also tried body pillows in his bed so he would feel as if someone is laying by him. This worked for me for a while.
Maybe being four is just scary given new comprehension of ideas and learning new concepts. I think my four year old tests me to see what he can get away with and this is one thing that he can control. when he sleeps. So, good luck, and if this sparks any ideas please send them my way. You are not alone. :-) B.