WhatsApp returns to the Windows Phone store, just in time for the weekend
Initial reports about WhatsApp being removed tied the decision to compatibility factors with Windows Phone 8.1 developer preview, but it actually turned out to be due to a problem with Windows Phone 8 and the current GDR3 update which began pushing out last year.
The problem had to do with how notifications were handled on what is still the current “official” version of Windows Phone. There were not a whole lot of details provided, but it likely had to do with the feature that enabled custom notification tones that are available for Windows Phone devices running the GDR3 update.
See the source link to get your WhatsApp reinstalled if you removed it from your device.
source: Windows Phone Store via Joe Belfiore (Twitter)