Have other 4 year old girls come over and let your daughter go with her friend to watch her potty. And make a big deal out of the other girl going to the potty & maybe your daughter will want to go herself.
stop putting diapers/pull-ups on her and let her pee/poop herself and make HER CLEAN IT UP! Kids hate being in their own pee/poop and cleaning themselves up and their clothes is even worse...i've watched this work with mutiple children. it's worth a try but you cant back down, she cleans herself EVERY time
I put then in little sun dresses around the house and no panties for about a week if they make a mess they clean it up.Along with you saying. something like. Why did you do that, you know where that stuff belongs with an upset voice. Also if she uses it offer 1 M&M. Only one for pee 2 for poo. That worked wonders for me. Took about 3 tiring weeks.
Go buy her some real panties and tell her and when your up with her let her put them on and tell her that if she wets them then she'll have to wear the diapers too. When she's in bed put the panties on and tell her to let you know when she needs to go and put the diaper or pull up OVER the panties just in case she wets herself. My DD is 3.5 years old and I just started a week ago and she now doesn't have to wear a diaper while up. While asleep though it's off and on. Just be patient. We bought her a potty that lets us know when she pees or poops and that helped a lot also.