Latest: Try this tutorial for getting WhatsApp Plus working on your devices (If nothing else works)
Here is one more tutorial which can help you in using any version of WhatsApp on Nokia X, Nokia X+ and Nokia XL
While I was able to install WhatsApp from 1MobileMarket on Nokia X, with latest update which takes WhatsApp on 1MobileMarket to latest version even that option is gone. Now only option left is trying to sideload older WhatsApp version directly from apk file. Here is the link to one of the working WhatsApp versions on Nokia X.
Just make sure that, you have done this already, open Settings, scroll down and tap on security —>Here, tick the box in front of Unknown Sources–>Accept the warning.
You can watch our Nokia X and Nokia XL hands-on videos including unboxing, UI demo, full settings walk-through, native apps and review etc by clicking here and here. Catch the full Nokia X and Nokia XL coverage including extensive hands-on, camera comparison, display test, gaming and full review by clicking here and here.
Now, coming to the current situation, while we can explore workarounds for installing WhatsApp on Nokia X, it is far from ideal situation. Nokia must take it on priority to sort out this weird issue, as it impacts one of the most used and nearly a “deal-maker or deal-breaker” app. Hope, Nokia / Microsoft Mobile is listening!