setting a dropdown list to its default value c#

I have a dropdownlist which has a one hardcoded line as follows.

ddlDepartment.Items.Insert(0, new ListItem("Select the Department", "0"));

after clicking a button I need to set the 0th value. any tip? TIA.

How many English words
do you know?
Test your English vocabulary size, and measure
how many words do you know
Online Test
Powered by Examplum