On December 31, WhatsApp ended support for Windows Phone 7.
Is there a way to force the app to continue working anyway?
I'm on a Nokia Lumia 610 if that helps.
This means that if you are currently using WhatsApp on a Windows Phone 7, you will be able to continue to use WhatsApp on that phone during this period.
However, as part of this process, after July 1st, 2016 it will not be possible to create a WhatsApp account on a Windows Phone 7 nor move a WhatsApp account to a Windows Phone 7.
It means that only creation or moving an account to WP7 will become impossible. Existing WhatsApp account will remain untouched, so keep using it... and don't reset your data :-)