It may have been removed (it happens) or even combined with another icon on the screen. That happens way more than you might think.
First check that it didn't get combined with another icon. If it did, they are pretty easy to separate. When you open the dual one to make your choice, just 'tap', 'hold' and 'drag' the one icon off the other and to the main screen. That will separate them.
If it isn't combined with another (after looking) you should be able to locate it by "tapping" and "holding" the background of your home screen. It will bring up a list of things, over a few tabs, that can be added to your home screens. Your icon should be in there.