How to reset the calendar

Hi i am new to asp.net, so, sorry if my question is very basis. Please help me can?
My problem is that i want to reset the calendar when the user click on other functions to browse an event.
Example, initially when user used the calendar to browse the event available in the database, later he switch to use another function(e.g by venue), but then back to use the calendar again. If there any way i can use to reset the calendar to today's date, so that whenever the user click on date button(i use a link button to control the calendar visibility), the calendar will so today's date and not the date that the user previously select.
 i have tried to use "Calendar1.SelectedDate = System.DateTime.Now" , but it not working at all. The date in the calendar is successfully set, but the calendar did not show it. Can help me? Below is part of my code

protected void lbtn_Date_Click(object sender, EventArgs e)
    {
&nb ...