try as
query = "Update LIKey SET Desc=@desc,Example=@exp WHERE LIKeys=@LIKeys";
cmdUpdate.CommandText = query;
cmdUpdate.Connection = OCon;
cmdUpdate.CommandType = CommandType.Text;
cmdUpdate.Parameters.AddWithValue("desc",txtDesc.Text);
cmdUpdate.Parameters.AddWithValue("exp",txtExample.Text);
cmdUpdate.Parameters.AddWithValue("LIKeys",txtLIKey.Text);
cmdUpdate.ExecuteNonQuery();