Look in your app drawer. He may have deleted just the shortcut on the home screen. If that's the case, when you find Chrome in the app drawer, long-press it, then move it (a small version of the home screen will appear) and move it to the home screen. that will create the shortcut you used to have.
If he uninstalled it from the phone, use Play to find it in the Play Store and install it. If it doesn't show up on the home screen after that, see the above paragraph to put it there.
(And the next time he wants to muck around with your phone, tell him to muck around with his own phone.)