calendar initialize in wpf

I am using a calendar in my project and after using the开发者_如何学Python information

i want to set it back to default and i am having a trouble with it

Edit :

sorry for any misunderstanding, lets say the user changed the calendar,

how can i set it to the way it was before the user changed it (no marks of dates and back to the previous way it was)

okey i found it:

calendar.SelectedDate = null;
calendar.DisplayDate = DateTime.Today;