If you've been using Air Drop on your iPhone, and it's October 2017 or later, it probably stopped working, and you can't find it in what used to be the familiar area of your control center. For whatever reason, it was turned off during the last update of your phone's software. No, I have no idea why they do this kind of stuff, I'm sure they have a reason.
To make it worse, the button that used to show up on the control center for Air Drop is now gone. It's hidden down a layer that you can only get to by touching a strange looking button (pictured above) that looks kinda like a robot with a headache. Push and hold down the "robot with a headache" button and another menu appears, and that's where you can turn Air Drop back on.
|The hidden "mystery menu". And there it is!|
I like to set it to contacts only, but you can set it to everyone if you like. But if it's set to off (and it probably is) you need to change it. It would be nice if the button just said "on" and "off", and if it wasn't hidden in a mystery menu that was invisible, but I'm sure they meant well.
Hope this helps.