WhatsApp automatically makes backups of your chat history every day at 4 AM and you can uninstall and reinstall WhatsApp to restore messages from this copy.
Note: You will not be able to access Voice Messages sent and received prior to reinstallation.
If you are unable to restore your chats, unfortunately, we can not restore your chats, contacts or multimedia files for you.
The first step is to check the time of the most recent backup file created. Note that any messages deleted from your phone before the backup was created, will not be restored.
To check the time of your last backup:
Then, uninstall and reinstall WhatsApp. After reopening WhatsApp, you will be asked: "Would you like to restore your message history from backup?", choose restore.
Important: You will lose all the messages you have sent and received since the backup was created.
We also suggest periodically exporting important chat histories to have copies saved outside of WhatsApp.
Learn how to restore messages on: Android | iPhone | BlackBerry | Nokia S60 | BlackBerry 10
Cheers,
WhatsApp Support Team