Mọi người xem hộ em với ạ. Em chạy chương trình mà nó không đưa ra kết quả. En chưa biết gì, mong mọi người giúp đỡ ạ

[lop_CSDLG301 (Lớp Csdlg301)]

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <stdlib.h>
struct HD {
	int stt, sl , dgia, tt;
	char mahh[10], tenhh[30];
          };
int main()
{
HD a[2];
int i,j ;
FILE *f;
	menu:
    printf("\n QUAN LI BAN HANG");
    printf("\n1. Nhap thong tin hoa don\n");
    printf("2. Tim kiem mat hang.\n");
    printf("3. thong ke theo ten hang.\n");
    printf("Chon: ");
    scanf("%d",&j);
f=fopen("E://hoadon.txt","w");
	switch(j)
    {
    case 1:

for(i=0; i<2 ; i++)
{
printf("\n Nhap thong tin hoa don thu%d: ",i+1);
printf("\n Nhap stt : ");
scanf("%d",&a[i].stt);
printf("\n Nhap ma hang hoa : ");
fflush(stdin);
gets(a[i].mahh);     
printf("\n Nhap ten hang hoa : ");
fflush(stdin);
gets(a[i].tenhh);
printf("\n Nhap so luong : ");
scanf("%d", &a[i].sl);
printf("\n Nhap don gia: ");
scanf("%d",&a[i].dgia);
a[i].tt=a[i].sl*a[i].dgia;
} ;break;
case 2:
{
char ten[30];
int k=0;
printf("\n ten mat hang can tim kiem:"); 
fflush(stdin);
gets(ten);
for(i=0;i<2; i++)
{
if(strcmp(a[i].tenhh,ten)==0)
{
printf("\n|  %-3d|     %-6s|    %-24s|%9d |%8d |%9d",a[i].stt,a[i].mahh, a[i].tenhh,a[i].sl,a[i].dgia,a[i].tt);
k++;
}
}
if(k!=0)
{
printf("");
}
else
{
printf("khong co ten mat hang");
}
break;
case3:
{
printf("\n---------------------------------------------------------------------------");
fprintf(f,"\n---------------------------------------------------------------------------");
printf("                               QUAN LI BAN HANG                                 ");
fprintf(f,"\n                          QUAN LI BAN HANG                              ");
printf("\n--------------------------------------------------------------------------------");
fprintf(f,"\n--------------------------------------------------------------------------------");
printf("\n| STT |     Ma HH     |           Ten Hang           | So Luong | Don gia | Tong tien");
fprintf(f,"\n| STT |     Ma HH     |           Ten Hang           | So Luong | Don gia | Tong tien");
printf("\n---------------------------------------------------------------------------");
fprintf(f,"\n---------------------------------------------------------------------------");
for(i=0; i<2;i++)
{
printf("\n|  %-3d|     %-6s|    %-24s|%9d |%8d |%9d",a[i].stt,a[i].mahh, a[i].tenhh,a[i].sl,a[i].dgia);
fprintf(f,"\n|  %-3d|     %-6s|    %-24s|%9d |%8d |%9d",a[i].stt,a[i].mahh, a[i].tenhh,a[i].sl,a[i].dgia);
}
}
}
fclose(f);
getch();
goto menu;
getch ();
return 0;
}
}