Top 5: uninstall, and reinstall to restore WhatsApp
This is the basic way to restore WhatsApp data. You can find the uninstall option in WhatsApp setting or you can directly delete it on home screen of iPhone.When you reinstall WhatsApp on your iPhone, a messages windows will pop out to ask you whether resotre the data, you just need to tap "restore".The WhatsApp will help you restore the chat backup.Top 4: Restore from manual backup files
You may manually backup your WhatsApp chat messages regularly. When you lost WhatsApp chat history, you can restore from manubackup file. You can choose the bakcup file when you enable restore feature in WhatsApp setting.Top 3:Try to rename the backup files
A trick about WhatsApp backup we need to know- the auto backup maken by WhatsApp just will keep last seven days chat history. Over 7 days, those old backup file will be overwritten by the new. So, when you want to keep those backup files to restore in someday, you can rename the backup file with a file management app. for example, you can choose the backup file you want to keep for a long time, and change the name from "msgstore-YYYY-MM-DD.1.db.crypt" to "msgstore.db.crypt".Top 2:Recover from iTunes or iCloud
There is no doubt that, iTunes and iCloud is the best helper for iOS device, we can use them to recover WhatsApp messages from iPhone. Just go to iTunes to restore backup when you lost WhatsApp chat history. Or you can go to WhatsApp Settings > Chat Settings > Chat Backup, here are the backup files made by iCloud.Top 1:Recover WhatsApp chat messages with recovery tool
The top 5- top 4 ways are the default ways provided by WhatsApp officially. Indeed, we can use other the 3rd-party useful tools to get back WhatsApp messages from iPhone for free. The most important is that backup recovery from default ways will overwrite the present state of WhatsApp, it means you can get back old messages, but at the same time you may lose the new. And the specific messages in backup file are invisible, thus you have no choice! A good WhatsApp recovery software can solve these problems, you can use it extract and recover WhatsApp messages from iPhone to computer. If you are interetd, you can know more here: http://www.any-data-recovery.com/topics/whatsapp/extract-iphone-whatsapp-messages-for-free.htmlVideo introduction about WhatsApp Recovery software: