reading words from file and sort them alphabetically in a list in C

[Adm666]

im intending to write a code that reads words and the lines that it appears at from a file and sort the words alphabetically in a linked list then prints them.
so far i've made out this... but it doesn't print them in alphabetic order and it prints duplicates as well (which it shouldn't be doing so)
any help ?

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define SIZE 1023
#define LENSTR_(x) #x
#define LENSTR(x) LENSTR_(x)
#define LEN  7

/* Struct for word and lines that appears in */
struct wordStruct {
char *word;
char *lines;
struct wordStruct *next;
};

static int compare_words(const struct wordStruct *a, const struct wordStruct *b) {
    return strcmp(a->word, b->word);
}

static struct wordStruct *insert_sorted(struct wordStruct *headptr, char *word, char *lines) {
    /* Struct head */
    struct wordStruct *pp = headptr;
    struct wordStruct *prior = headptr;
    struct wordStruct *ptr = malloc(sizeof(struct wordStruct));
    /*check for duplicate */
    while ( pp != NULL) {
        if ( strcmp ( word, pp->word) == 0) {
            size_t length = strlen ( pp->lines);
            char *temp = realloc ( pp->lines, length + strlen ( lines) + 3);
            if ( temp == NULL) {
                fprintf ( stderr, "problem reallocating\n");
            }
            else {
                pp->lines = temp;
                strcat ( pp->lines, ",");
                strcat ( pp->lines, lines);
            }
            return headptr;
        }
        pp = pp->next;
    }
    /* Allocate heap space for a record */

    if (ptr == NULL) {
        abort();
    }

    /* Assign to structure fields */
    ptr->word = malloc ( strlen ( word) + 1);
    strcpy ( ptr->word, word);
    ptr->lines = malloc ( strlen ( lines) + 1);
    strcpy ( ptr->lines, lines);
    ptr->next = NULL;

    pp = headptr;
    prior = headptr;

    /* Store words in alphabetic order */
    if ( headptr == NULL) {
        headptr = ptr;
    }
    else {
        while (pp != NULL && compare_words(ptr, pp) > 0) {
            prior = pp;
            pp = pp->next;
        }
        if ( pp == headptr) {
            ptr->next = headptr;
            headptr =  ptr;
        }
        else {
            prior->next = ptr;
            ptr->next = pp;
        }
    }

    return headptr;
}

static struct wordStruct *read_words (FILE *f, struct wordStruct *headptr) {
    char x[SIZE + 1];
    char ws[SIZE + 1];
    char line[SIZE + 1];
    char *pws = ws;
    int lines = 1;
    /* assumes no word exceeds length of 1023 */
    while (fscanf(f, "%"LENSTR(SIZE)"s", x) == 1) {
        /*printf ( "%s at line %d\n", x, lines);print the word and line */
        sprintf ( line, "%d", lines);
        headptr = insert_sorted(headptr, x, line);

        if ( fscanf ( f, "%"LENSTR(SIZE)"[ \n\t\r]", ws) == 1) {/*scan space, newline, tab and carriage return*/
            pws = ws;
            while ( *pws) {
                if ( *pws == '\n') {
                    lines++;/*count newlines*/
                }
                pws++;
            }
        }
    }
    return headptr;
}

int main(int argc, char **argv) {
    /* Snitialize empty list */
    struct wordStruct *headptr = NULL;
    /* Snitialize current */
    struct wordStruct *current;
    struct wordStruct *temp;
    FILE *fileptr = NULL;

    if ( NULL == ( fileptr = fopen ( "test.txt", "r"))) {
        fprintf ( stderr, "could not open file\n");
        return 0;
    }

    /* Insert words in list */
    headptr = read_words( fileptr, headptr);

    fclose ( fileptr);

    current = headptr;
    while (current != NULL) {
        printf("%s appears in lines %s.\n", current->word, current->lines);
        current = current->next;
    }
    /*release memory*/
    current = headptr;
    while (current != NULL) {
        temp = current;
        current = current->next;
        free ( temp->word);
        free ( temp->lines);
        free ( temp);
    }
    return 0;
}

[Adm666]

also when i try to put :

   int u=0;
   while( x[u] ) 
   {
      x[u] = (tolower(x[u]));
      u++;
   }

in line 90 so it'll insert the words in lower letters to the list, but it does nothing why?