For download the whatapps in your device for this you are simply follow some of the steps.
Steps to install whatsapp on sony xperia go:
1.make sure you have an internet connection
2.now go to the main menu
3.go to the google play store and find the list of free apps where you can find the whatsapp
4. search the new latest whatapps apps
5.after that tap on the download option
6. now install in your device.
7. at the last restart your device.
I have got your problem if you are not able to download it from Play store then follow this method.
1.Firstly go to ‘Google.com’ in your PC.
2.And then tap on the Play option available in google home page.
3.Now get sign in to your account in play store.
4.And then search for Whats app and go for the option of ‘Install’ tab.
5.Later go for the option of turning on the internet connection of your phone.
6.The app gets installed on its own.