Setting dropdownlist selecteditem programmatically

Well if I understood correctly your question. The Solution for setting the value for a given dropdownlist will be:

dropdownlist1.Text="Your Value";

This will work only if the value is existing in the data-source of the dropdownlist.

Assuming the list is already data bound you can simply set the SelectedValue property on your dropdown list.

list.DataSource = GetListItems(); // <-- Get your data from somewhere.
list.DataValueField = "ValueProperty";
list.DataTextField = "TextProperty";
list.DataBind();

list.SelectedValue = myValue.ToString();

The value of the myValue variable would need to exist in the property specified within the DataValueField in your controls databinding.

UPDATE: If the value of myValue doesn't exist as a value with the dropdown list options it will default to select the first option in the dropdown list.

ddlData.SelectedIndex will contain the int value To select the specific value into DropDown :

ddlData.SelectedIndex=ddlData.Items.IndexOf(ddlData.Items.FindByText("value"));

return type of ddlData.Items.IndexOf(ddlData.Items.FindByText("value")); is int.

Here is the code I was looking for :

DDL.SelectedIndex = DDL.Items.IndexOf(DDL.Items.FindByText("PassedValue"));

Or

DDL.SelectedIndex = DDL.Items.IndexOf(DDL.Items.FindByValue("PassedValue"));