#include <stdio.h>
#define IN 1
#define OUT 0

int main()
{
  while (1)
  {
    FILE *fptr1;
    char filename[100];
    printf("Enter the filename to open for reading n");
    scanf("%s", filename);
    fptr1 = fopen(filename, "r");

    int c, nl, nw, nc, state; // These variables aren't being reset.

    while ((c = fgetc(fptr1)) != EOF)
    {
      ++nc;
      if (c == 'n') ++nl;
      if (c == 't' || c == 'n' || c == ' ') state = OUT;
      else if (state == OUT)
      {
        state = IN;
        ++nw;
      }
    };
    printf("Lines: %d Words: %d Characters: %dn", nl, nw, nc);
  }
  return 0;
}

Enter the filename to open for reading
data.txt
Lines: 6 Words: 15 Characters: 81
Enter the filename to open for reading
data.txt
Lines: 12 Words: 30 Characters: 162
Enter the filename to open for reading