4 yr old won't sleep alone?

This is a supernanny tecnice. Put her into her bed and say goodnight. If she comes out put her back into her bed and say it's bedtime darling. Next time she comes out say "It's bedtime" and put her straight back into her bed. Next time she gets out you say nothing and put her into bed. Keep going and just ignore any cries you hear. It seems cruel but, it works.