School Nursery

so little girl has startes school nursery today she never has had a problem using toilets in other places or even asking family to use the toilet who she hasnt seen for a while but shes now gone 2 days 7 hours without using the toilet and i dont know what to do i think its because they use the toilet themselves without an adult and she doesnt do it what can i do to help her go at school i asked her teacher to make sure she went today and she didn't