c++ – merge sort function in linked list

I am trying to implement merge sort in a linked list in c++. When I execute my code, it runs infinitely no. of time. When I debug it, I found that my mergesort function runs only for the left half infinite number no. of times. That function never called for the right half. I am pasting my whole code link here. Can anyone tell me why the function runs infinitely and what modifications I have to make to my code?

struct Node
int data;
struct Node *link;

Code link: https://pastebin.com/pUdQTGWD

In the above link, ins function is used to insert the node. getmid function is used for getting the address of the middle node. merge function is used to sort the left and right half. And mergesort function is used to divide the list into 2 half and call each half.display function is used for print linked list.