Prefiero usar SMO para restaurar una copia de seguridad:
Microsoft.SqlServer.Management.Smo.Server smoServer =
new Server(new ServerConnection(server));
Database db = smoServer.Databases['MyDataBase'];
string dbPath = Path.Combine(db.PrimaryFilePath, 'MyDataBase.mdf');
string logPath = Path.Combine(db.PrimaryFilePath, 'MyDataBase_Log.ldf');
Restore restore = new Restore();
BackupDeviceItem deviceItem =
new BackupDeviceItem('d:\MyDATA.BAK', DeviceType.File);
restore.Devices.Add(deviceItem);
restore.Database = backupDatabaseTo;
restore.FileNumber = restoreFileNumber;
restore.Action = RestoreActionType.Database;
restore.ReplaceDatabase = true;
restore.SqlRestore(smoServer);
db = smoServer.Databases['MyDataBase'];
db.SetOnline();
smoServer.Refresh();
db.Refresh();
Necesitará referencias a Microsoft.SqlServer.Smo, Microsoft.SqlServer.SmoExtended y Microsoft.SqlServer.Management.Sdk.Sfc