How do I call function in inhereted script?

The function you're looking to call in the parent script must be public, then just call it as you would any other function.

 using UnityEngine;
 using System.Collections;
 
 public class Parent : MonoBehaviour 
 {
     public void ParentFunction()
     {
         Debug.Log("Parent function was called!");
     }
 }
 
 using UnityEngine;
 using System.Collections;
 
 public class C$$anonymous$$ld : Parent 
 {
     // Use t$$anonymous$$s for initialization
     void Start () 
     {
         ParentFunction();
     }
 }