不知道为什么这样子运行不起来

用C语言读取文章中的单词（假设不在行中分开，暂时不转换大小写），并将其保存在二叉树中，想着顺了几遍感觉没有什么问题了，结果直接是跳出异常，不知道出了什么问题？竟然连第一个也没插入，实在搞不懂

#include <stdio.h>
#include <stdlib.h>
typedef struct words
{
    char word[15];
    int n;
} item;
item * node;
typedef struct nodes
{
    item gather;
    struct nodes * left;
    struct nodes * right;
} Node;
void readfile(FILE * fp, Node *);
int main()
{
    FILE *fp;
    fp = fopen("try.txt", "r");
    Node *root;
    root = NULL;
    readfile(fp, root);
    printf("%s", root->gather.word);
    return 0;
}
void readfile(FILE * fp, Node * root)
{
    char ch;
    char cht;
    Node *test;
    int ss = 0;
    while (!feof(fp))
    {
        ss++;
        test = root;
        ch = getc(fp);
        while (test != NULL )
        {
    
            FILE *helper = fp;
            int n = 1;
            if ((test->gather).word[0] == ch)
                while ((cht = getc(helper)) != '\n' && (cht ) != ' ')
                {
                    if ((test->gather).word[n] == cht)
                    {
                        n++;
                        continue;
                    }
                    else
                        break;
                }
            if ((cht ) == '\n' && (cht) == ' ' && (test->gather).word[n] == cht)
            {
                test->gather.n++;
                fp = helper;
            }
            else if ((ch < (test->gather).word[0]))
    
                test = test->left;

            else
    
                test = test->right;

        }
        if (test == NULL)
        {
            test = (Node *)malloc(sizeof(Node));
            ((test->gather).word[0]) = '\0';
            ((test->gather)).n = 0;
            test->left = test->right = NULL;
        }
        if (test->gather.word[0] == '\0')
        {
            test->gather.word[0] = ch;
            test->gather.n++;
            int x = 1;
            while ((ch = getc(fp)) != '\0' && (ch) != ' ')
            {
                test->gather.word[x] = ch;
                x++;
            }
            test->gather.word[x] = '\0';
        }
    }
}

root使用时一直是空指针，所以异常，需要先分配空间