Try rebooting your phone.... also, are you using the stock TW launcher that came with the phone or did you install a 3rd party launcher like Nova, Apex, etc..? Make sure you didn't accidentally "hide" the app.
Using stock launcher, checked hidden apps, and restarted. Still no where to be found.
Did you deactivate it? Go to the app manager and go all the way to the bottom of the app list to see the deactivated ones (they do not appear in alphabetically order with the other active apps).
SOLVED! It was deactivated. Thank you!!!!