thanks again for replying..
actually my struct isa someth like..

in file stack_check.c

struct node
int element;
struct node* next;

and in other file where i am actually implementing stack for tree operations like storing the nodes of the tree onto the stack in file name tree_stack.c .
the rudimentary file is smth like...(just modifying in your code)

extern struct node* nd;
struct st
struct node* nd;
struct st* nxt;

void display_stack()
struct st* curr;
printf("%d",curr->nd->element); // here its showing error

return 0;
thanks again..