rand(); function is always creating same random number [duplicate]

I have got a problem about rand(); function in C language. My teacher gave me a assignment about finding the random generated number. ı used rand(); function for generating a random number but my program always generating the same number (42). How can I solve this problem?

#include "stdlib.h"
#include <stdio.h>
#include <dos.h>
#include <windows.h>
#include <locale.h>

int main()
{
    int rnd, number=0;          //Value definitions.

    setlocale(LC_ALL, "Turkish");       //Without this line, line 48 is working incorrectly.

    printf("\t\t\t\t-----------------------------------------\n");
    printf("\t\t\t\t|                    |\n");
    printf("\t\t\t\t|      Welcome to Guess Number Game      |\n");         //Introduction.
    printf("\t\t\t\t|                    |\n");
    printf("\t\t\t\t-----------------------------------------\n");

    printf("Game is starting...\n");
    printf("3\n");
    Sleep(1000);
    printf("2\n");
    Sleep(1000);            //Game start countdown.
    printf("1");
    Sleep(1000);
    system("cls");

    rnd = 1 + rand() % 1000;        //Random number is created.

    printf("Let's try to guess the number that in my mind :)\n\n");
    for (int i = 1; number != rnd; i++)
    {
        printf("What is your guess?\n");
        printf("Number: ");                 //"For structure" is defined for finding the attempts.
        scanf_s("%d", &number);
        printf("\n");

        if (number < rnd)
        {
            printf("The secret number is greater than your guess. Try again...\n");
        }
        else if (number > rnd)
        {
            printf("The secret number is smaller than your guess. Try again...\n");
        }
        else
        {
            printf("Congratulations!!!  You know the number at your %d’th guess", i);
        }
    }

    system("PAUSE");
    return 0;
}