I've remade a program to store student database using linked list. Can anyone help me to find whats wrong with my code when I try to display the list of student with their information (It displays nothing)
Your problem is you're calling processMenu recursively at lines 69 and 93.
For example, after adding the first student, you call processMenu which results in two processMenu frames on the stack. The second instance of processMenu gets new occurrances of it's local variables, specifically head which is initialied to NULL. If you now choose list, the list will appear empty.