When a new contact is added to your phone's address book, WhatsApp Messenger usually automatically detects the contact and adds him or her to your Favorites list. However, if you are sure that your contact has an account, but he or she does not appear in your WhatsApp contact list, you may need to manually refresh the application.
Refresh WhatsApp Contact List
This article will walk you how to refresh your contact list on WhatsApp for Android and WhatsApp for iPhone.
Display WhatsApp Contacts on Android
Open WhatsApp Messenger and tap on the New Chat button to access your contact list:
Next, tap on the Menu button > Refresh. Your contact list will immediately update to reveal any and all contacts available on WhatsApp:
Display WhatsApp Contacts on iPhone
Launch WhatsApp and go to your Favorites tab. Scroll to the top of your Favorites list and then pull the list down with your finger.
WhatsApp will now refresh your contacts list. Your Favorites will be sorted alphabetically, and any hidden or deleted contacts will be restored.