Contacts data is one of the most sensitive just like precious locker in whole bank; No one can do provocation with contact app. It’s hence that, may be you lost or clear all saved contacts from your iOS device locally and then in iCloud as well after sync it. My suggestion about contact is take iPhone contacts backup time to time. After lost from device, there are a very less possibilities of recover or restore after iPhone contacts gone, find from older iCloud Backup or Mac/ PC using iTunes.
Due to auto sync saved contacts from different mail account Gmail, Outlook, Yahoo and Bing. You may be surprise on Contact suddenly disappeared from iPhone contact app. This is my personal experience, and I revert it back in app using below steps, let’s see what the circumstances is and how we reappear all contacts?
How to recover iPhone contacts gone, Deleted or Not Showing: iOS 9
Early morning, I setup Gmail in iPhone mail app. After successfully login, Screen say me to enable contacts, Calendar and note sync to iPhone automatically (Default selection is all enabled). After some time, I open contact app there all contacts (704) not showing. And only showing Gmail contacts (4).
Now I found hidden contacts list from app settings. So you can manually choose which contacts group you would like to show within app.
Step 2: All created default groups are: All iCloud, All Gmail..
Step 3: Tap on All iCloud, (After setup on new iPhone with iCloud login, Apple saved all contacts in your iCloud account first)
Here is an also option for only access other’s group list or not icloud.
Above step also useful for whom finding the way for iPhone contacts gone and restore all contacts from iCloud without iCloud backup or iTunes. Enable iCloud contacts group in contact app.