Please I know these things just I don't know what loop statement I should add to make It .as..requirments

Why don't you stop and think about what you're asking. You don't need recursion to do this ( although I'd pay money to see you hand that code in and have your teacher ask you to explain it ). iostream.h is NOT C++. A main() that does not return an int is not C++. Again, if your teacher has given you these ideas, your class sucks and you need to leave it. Ditto the use of printf. However, to make a C program that does what you want, just stop and think about what you're asking. You want to input a number, then work through the alphabet and print each letter X times. Looking through your code, it should be blatantly obvious why your code doesn't even do that for the numbers 1-3. If you can't work THAT out, you definitely need to give up on programming. Then stop and think. Instead of typing in code to deal with each number you want to support, what concept is ALREADY in your code that allows you to execute some code a specific number of times ?

'Any amount' is a bit pretentious (you've not such a computational power...). Anyway, you may do better than you did, though you've to go recursive ("To Iterate is Human, to Recurse, Divine" - L. Peter Deutsch):

void seq(char * str, unsigned int level, unsigned int depth)
{
  for (char c='A'; c<='Z'; c++)
  {
    str[level]=c;
    if ( level == depth-1 )
      printf("%s\t",str);
    else
      seq(str, level+1, depth);
  }
}
const int MAX_DEPTH = 10;
void main()
{
  char str[MAX_DEPTH+1] = {0};
  unsigned int depth;
  printf("enter a number between 1 and %d: ",  MAX_DEPTH );
  if (scanf("%u", &depth) != 1)
    return;

  depth %= MAX_DEPTH;
  seq(str,0, depth);
}

As Rajesh already noted, the choice between C or C++, is irrelevant here.
:)

In addition to the fact that you're using C, and not C++ ( as others have said, is void main valid C ? ), I will just add that you should expect that your teacher knows how to use google and is already aware that someone has given you some code. You should talk to your teacher before they talk to you, if you don't want to be failed for cheating.

If your teacher thinks this is valid C++, you should leave the class, and not wait to be kicked out.