From of today several people are complaining that the are banned from WhatsApp.
This is probably because you have a third party app installed like “WhatsApp plus”
Reportedly after 12 AM IST on 21st January 2015, WhatsApp, the widely popular messaging application, has started temporarily banning users for 24 Hours who are currently using any third-party WhatsApp clients and are being directed to download the official app on the Play Store instead.
In an attempt to clear up why this is happening, Whatsapp team explained via its FAQ website, that it is against ‘Terms of Service’ to use WhatsApp Plus or any other 3rd-party unofficial app.
Why am I banned and how do I get unbanned?
WhatsApp Plus is an application that was not developed by WhatsApp, nor is it authorized by WhatsApp. The developers of WhatsApp Plus have no relationship to WhatsApp, and we do not support WhatsApp Plus. Please be aware that WhatsApp Plus contains source code which WhatsApp cannot guarantee as safe and that your private information is potentially being passed to 3rd parties without your knowledge or authorization. Please uninstall your application and install an authorized version of WhatsApp from our website or Google Play. Then, you will be able to use WhatsApp.
If you have a third party app installed in your smartphone, we suggest you to uninstall it if you don’t want to go through that 24 hour ban.