Check with some this i have done small changes ,just storing values in viewstae and rebinding to textbox
protected void BtnSubmit_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(_connString); con.Open(); SqlDataAdapter da = new SqlDataAdapter("Select * from Equipment_Inventory", con);
SqlCommandBuilder builder = new SqlCommandBuilder(da); DataSet ds = new DataSet("Equipment_Inventory"); da.Fill(ds, "Equipment_Inventory");
DataTable Equipment_InventoryTable = ds.Tables["Equipment_Inventory"]; DataRow row = Equipment_InventoryTable.NewRow();
row["Dept_code"] = TxtDeptCode.Text;
row["Dept_desc"] = TxtDescription.Text;
row["Dept_telno"] = TxtTelephoneNo.Text;
Viewstate("Dept_code")= TxtDeptCode.Text;
Viewstate("Dept_telno")= TxtTelephoneNo.Text;
Viewstate("Dept_desc") = TxtDescription.Text;
row["Dept_dirmgr"] = TxtDirector_Manager.Text;
row["Equipment_type"] = DDL_EquipmentType.SelectedItem.Text;
row["Maker"] = DDL_Maker.SelectedItem.Text;
row["Model"] = TxtModel.Text;
row["Serialno"] = TxtSerialNo.Text;
row["TagNo"] = TxtKKIA_GACA_tag.Text;
row["Assignedto"] = TxtAssignedTo.Text;
row["Location"] = TxtLocation.Text;
row["Dentry"] = DateTime.Now.ToString();
Equipment_InventoryTable.Rows.Add(row);
da.Update(ds, "Equipment_Inventory");
con.Close();
TxtDeptCode.Text=Viewstate("Dept_code");
TxtTelephoneNo.Text=Viewstate("Dept_telno");
TxtDescription.Text=Viewstate("Dept_desc") ;
TxtDirector_Manager.Text = "";
DDL_EquipmentType.SelectedItem.Text = "";
DDL_Maker.SelectedItem.Text = "";
TxtModel.Text = "";
TxtSerialNo.Text = "";
TxtKKIA_GACA_tag.Text = "";
TxtAssignedTo.Text = "";
TxtLocation.Text = "";
ScriptManager.RegisterStartupScript(this, this.GetType(), "RunCode", "javascript:alert('Inventory added Successfully');", true);
}