Whatsapp Upgrade unable to recover chat history

Hi,

I tried upgrading the watsapp from appstore and in this process i have lost my whatsapp chats totally.

What i have done?

- from appstore i upgraded my whatsapp.

- once it is completed, when i clicked on whatsapp icon on my iphone i could see "optimising" loading screen.

- since it was taking a while and i couldn't see it moving i killed the app.

Later when i click on watsapp icon on my screen i can see it as below

When i click on "Begin Recovery" i can see the progress bar showing the status as "completed 5% " but after that i see the below message on screen

I can no more see my old watsapp chats when i click on the watsapp icon from my home screen. But i can only view the badge notifications when people are sending me messages. kindly help.