These steps are to restore deleted WhatsApp chats using google drive. But before that, you must make sure your WhatsApp has backups on Google Drive. If yes, you can do these steps to restore your deleted chat on WhatsApp.
1. Delete your WhatsApp application and install it back.
2. Next, open WhatsApp and log in using your WhatsApp number.
3. Then, you will get options to restore your WhatsApp chats from Google Drive.
4. Select restore to get your deleted chats on WhatsApp.
5. If you have a backup on google drive before deleting the chats, you will get the deleted chats back.