aha. why? what happens? Maybe describing the problem would help...
Normally you just have to wait for the sms from whatsapp team. If its not coming, try again.
i also have a lumia 625 , @09876 tap on store and search whats app,facebook, viber or any other apps you like. in results you will get your app . to download them you need to have a 3g data or wifi.