مشکل در وصل شدن به بانک اطلاعاتی

سلام
بنده با توجه به راهنمایی های دوستان در سوال قبلی بنده فهمیدم که user id همیشه sa هست و پسورد رو هم تغییر دادم به 123
الان به یک مشکلی خوردم
 

این ها کدهایی هستن که بنده از روی ویدیو زدم
این هم متن ارور

(System.Data.SqlClient.SqlException

 HResult=0x80131904

 Message=A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)

 Source=.Net SqlClient Data Provider

 StackTrace:

  at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling, SqlAuthenticationProviderManager sqlAuthProviderManager)

  at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)

  at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)

  at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)

  at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)

  at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)

  at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)

  at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)

  at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)

  at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)

  at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)

  at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)

  at System.Data.SqlClient.SqlConnection.Open()

  at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)

  at System.Data.Common.DbDataAdapter.Fill(DataTable[] dataTables, Int32 startRecord, Int32 maxRecords, IDbCommand command, CommandBehavior behavior)

  at System.Data.Common.DbDataAdapter.Fill(DataTable dataTable)

  at WindowsFormsApp6.ContactRepository.SelectAll() in C:\Users\Amir\source\repos\WindowsFormsApp6\WindowsFormsApp6\Services\ContactRepository.cs:line 21

  at WindowsFormsApp6.Form1.Form1_Load(Object sender, EventArgs e) in C:\Users\Amir\source\repos\WindowsFormsApp6\WindowsFormsApp6\Form1.cs:line 29

  at System.Windows.Forms.Form.OnLoad(EventArgs e)

  at System.Windows.Forms.Form.OnCreateControl()

  at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)

  at System.Windows.Forms.Control.CreateControl()

  at System.Windows.Forms.Control.WmShowWindow(Message& m)

  at System.Windows.Forms.Control.WndProc(Message& m)

  at System.Windows.Forms.ScrollableControl.WndProc(Message& m)

  at System.Windows.Forms.Form.WmShowWindow(Message& m)

  at System.Windows.Forms.Form.WndProc(Message& m)

  at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)

  at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)

  at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Inner Exception 1:

Win32Exception: The system cannot find the file specified

)