WhatsApp Contacts Tab
WhatsApp in its recent update has changed how the UI looks , there is no more Contacts Tab as there was in the past, as you can see in the image below the Contacts Tab as we all remember is no more

How to Get Old WhatsApp Contacts Tab
I have covered a blog post tutorial showing how to unlock hidden WhatsApp Features , the same tutorial can be used to enable the old contact tab as shown above, you can achieve that by following :
- Open the Tutorial Post
- Scroll to "[Tutorial] Unlock Hidden WhatsApp Features" and follow it step by step
- After Installing the App Open It , Go to WhatsApp Tweaks turn on "Disable new UI(Status)"
- Enjoy the old contacts tab in whatsapp
How to find WhatsApp Contacts in New Version
WhatsApp has removed the Contacts Tab and to see your WhatsApp Contact List
- Open WhatsApp Chat
- In the right bottom corner you will find a green circle with white text icon
- Press that Icon and it will show you, your complete WhatsApp Contact List
- You can clearly see the updated WhatsApp contact list in the image below

On some Android Mobiles which have a lesser screen dpi are not yet updated to Nougat the Send New Message and see All Contacts button might appear next to the WhatsApp Chat search as shown below

Hope this Helps