Step 1: The very first solution to your problem is to restore it locally by UNINSTALLING the WhatsApp Application on your device.
Step 2: REINSTALL it again.
Step 3: SIGN IN YOUR ACCOUNT in the newly installed application. Then, you will be prompted with a message that says, you are able to restore your backup after reinstalling the application on your device.
Step 4: All you need is to press RESTORE and your problem will be gone. But you need to keep in mind that the backup for your WhatsApp history is only valid for 7 days and after a week, it will be gone and you will not be able to locally solve the problem.
OPTION 2: Retrieving Deleted WhatsApp Messages by A Data Recovery Software
Step 1: CONNECT YOUR MOBILE TO YOUR COMPUTER WITH A USB CABLE Step 2: ENABLE USB DEBUGGING THROUGH SETTING UP YOUR MOBILE PHONE Step 3: Choose the mode according to the operating system. Like this: android 2.3 or earlier, enter SETTINGS and click APPLICATIONS then click DEVELOPMENT and tick USB DEBUGGING Step 4: Next step that you should take is: SCAN AND ANALYZE THE DATA ON YOUR MOBILE.
Step 5: Lastly, you have to TAKE A LOOK AND RECOVER FILES FROM WHATSAPP HISTORY.