On similar lines

SinglyLinkedListNode n=head1;

if((head1==null)&&(head2==null))

{

return null;

}

if((head1!=null)&&(head2==null))

{

return head1;

}

if((head1 == null)&&(head2!=null))

{

return head2;

}

if(head1.data <= head2.data)

{
head1.next = mergeLists(head1.next, head2);

n=head1;

}

else if(head1.data > head2.data)

{

head2.next = mergeLists(head2.next, head1);

n=head2;

} return n;
}