doubly del_by_pos riad v er moto but prblm

#include<stdio.h>
#include<stdlib.h>
typedef struct data
{
    int a;
    struct data *next;
    struct data *prev;
} data;

data *head=NULL;
data *tail=NULL;


void ins_at_first(int x)
{
    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;
    new_node->prev=NULL;

    if(head==NULL)

    {
        head=new_node;
        return;
    }
    new_node->next=head;
    head->prev=new_node;
    head=new_node;

    return;
}
void ins_at_end(int x)
{
    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;
    new_node->prev=NULL;

    if(head==NULL)
    {
        head=new_node;
        return;
    }
    data *temp=head;
    while(temp->next!=NULL)
    {
        temp=temp->next;
    }
    new_node->prev=temp;
    temp->next=new_node;

    return;
}

void ins_at_nth(int n, int x)
{
    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;
    new_node->prev=NULL;

    if(head==NULL)
    {
        head=new_node;
        return;
    }

    if(n==1)
    {
        head->next=new_node;
        new_node->prev=head;

        return;
    }

    data *temp=head;
    n=n-2;

    while(n--)
    {
        temp=temp->next;
        if(temp->next==NULL)
        {
            new_node->prev=temp;
            temp->next=new_node;

            return;
        }
    }
    new_node->next=temp->next;
    new_node->prev=temp;
    temp->next=new_node;


    return;



}

void del_by_pos(int n)
{
    if(head==NULL)
    {
        printf("\n      List was Empty Previously\n\n");
        return;
    }



    if(n==1)
    {
       data *del=head;
       head=head->next;
        if(head==NULL)
        {

            tail=NULL;

            free(del);

            return;
        }

        head->prev=NULL;
        free(del);

        return;

    }
    data *del=NULL;
    data *temp=head;
    n=n-2;
    while(n-- && temp->next!=NULL)
    {
        temp=temp->next;

    }
    del=temp->next;

    if(del==tail)
    {
        temp=tail;
        temp->next=NULL;

        free(del);
        return;
    }
    temp->next=del->next;
    del->next->prev=temp;

    free(del);
    return;
}





void reset()
{
    head=NULL;
    tail=NULL;
    return;
}

void print()
{
    data *temp=head;
    if(head==NULL)
    {
        printf("Empty\n");

    }

    while(temp!=NULL)
    {
        printf("%d ",temp->a);
        temp=temp->next;
    }
    printf("\n");
}

int main()
{
    int a,v,w,x,n,m,o;
    while(1)
    {
        printf("1.Insert At First\n");
        printf("2.Insert At End\n");
        printf("3.Insert At n_th Position\n");

        printf("4.Delete By Position\n");
        printf("5.Delete By Value\n");

        printf("8.Print\n");
        printf("9.RESET LINK LIST\n");

        printf("\n 0 for Al-Bida{-)\n");
        printf("\n             Command:");
        scanf("%d",&w);
        if(w==1)
        {
            printf("Enter an integer Number:");
            scanf("%d",&x);
            ins_at_first(x);

        }
        if(w==2)
        {
            printf("Enter an integer Number:");
            scanf("%d",&x);
            ins_at_end(x);
        }
        if(w==3)
        {
            printf("Declear The Position:");
            scanf("%d",&n);
            printf("Enter an integer Number:");
            scanf("%d",&x);
            ins_at_nth(n,x);
        }

        if(w==4)
        {
            printf("\nDeclear The Specific Position:");
            scanf("%d",&n);

            del_by_pos(n);

        }


        if(w==8)
        {
            printf("\n            Result: ");
            print();
            printf("\n");
        }

        if(w==9)
        {
            printf("\n      Reseted Successfully\n");
            reset();
        }

        if(w==0)
        {
            printf("\n    Jajakalla_khayer..[muftY]\n");
            break;
        }
    }
}