MySqlConnection =new MySqlConnection（string）が機能しない

これを試してください

MySqlConnectionStringBuilder connBuilder = new MySqlConnectionStringBuilder();

                    connBuilder.Server = "localhost";
                    connBuilder.UserID = "root";
                    connBuilder.Database = "therapygame";
                    connBuilder.Password = "";
                    connBuilder.OldGuids = true;

                connection = new MySqlConnection(connBuilder.ConnectionString);