Did you just get yourself a Windows Phone device, or are looking to reinstall apps, but couldn’t find WhatsApp on the Windows Phone store. Don’t fret, you’re not alone. Apparently, WhatsApp yanked it off the store themselves.
According to WP Central WhatsApp decided it was necessary to unpublish the messaging app from the Windows Phone store, so as to address certain technical issues, particularly bugs that plague Windows Phone 8.1:
Unfortunately due to technical issues, we have chosen to un-publish WhatsApp Messenger on the Windows Phone platform. We are working closely with Microsoft to resolve the issues and hope to return to the store shortly. We apologize to our users for the temporary inconvenience.
It is not clear why they took the blanket embargo route, especially as most Windows Phone users are still on version 8.0. However, the app still works for those who already have it installed. Whatever you do, do not uninstall WhatsApp until this issues is fixed. For users who don’t have the app installed, but must have it, there is the option of installing from the wild using offline .xap files. Bear in mind that this highly frowned upon within the Windows Phone ecosystem.