if (ddlCity.Items.FindByText(Authenticate(StrConv(Request.QueryString["City"], VbStrConv.ProperCase).ToString())) != null)
ddlCity.Items.FindByText(Authenticate(StrConv(Request.QueryString["City"], VbStrConv.ProperCase).ToString())).Selected = true;
http://forums.asp.net/p/1238455/2256368.aspx