My whatsapp icon is missing
Things I would try:

a) Just reset the phone if you haven't done already(turn it off and on

b) Uninstall the app, remove the sd, and install it again. There might be a problem with your SD card, and if the app is automatically installed there, maybe that's the reason you can't see it

Which launcher are you using? I believe you can see the app in the settings -> applications list?