Contact icon on iphone 6s disappeared

I have always had the contacts icon on the bottom of my home screen since my iphone 6s was purchased. It suddenly disappeared while I was using it at work today. There is no "extra" folder on my phone; I have gone through every file and folder; even used the spotlight search and nothing was found. I really want that icon back!!! I would greatly appreciate any input. Currently: iOS 10.2.1

A couple of weeks of go, after stumping 6 Verizon techs, 2 on-line chat & 1 phone line Apple techs (which took about 4 hours, had to restore my phone, and then it locked up), I ended up at the Apple store because this same phone was adding contacts all by itself. After 1.5 hrs at the store, the only thing the techs could come up with was this: since it started about 4 updates ago, something isn't working right, and to uncheck all the email accounts, and only use the cloud. Which was missing contacts. I've spent about 10-15 hours getting contacts into the cloud and back into my email accounts. So.....am I looking at another problem "related" to updating? Restoring to factory default is NOT a way I want to go since I had so much trouble trying to fix the other problem.

THANKS!