Cannot install whatsapp in android 2.3.4
You should know that WhatsApp is no longer supported on devices running android 2.3 and below. Newer updates​ won't simply install. The support had to end on june, and we're on june. 

You should consider upgrading to a newer phone.

However, in some exceptions, WhatsApp can be installed when you download directly the APK file.

Try downloading the file from here.