If you have deleted some message accidentally or want to read someone’s chat who has deleted their chat history to protect from others, you can easily restore their messages. Everyday WhatsApp starts a scheduled backup at 4 A.M. This backup file is stored in your phone’s memory. You can restore that backup file and read the message that was deleted yesterday. You can check the old backups.
File Manager > WhatsApp > Menu Button > Settings > Chat Settings > Backup conversations.
Those messages which were present yesterday and were deleted today. You can restore them because when schedule backup was started those message were not deleted.
To restore your backup you simply have to uninstall WhatsApp. After that install your WhatsApp again with the same mobile number that you were using earlier on your phone. While installation WhatsApp will ask you to restore your backup file. Accept that and it will restore all the messages that were present on your WhatsApp yesterday.
There is a disadvantage of restoring WhatsApp backup file while installation. The messages that you received after the backup file was created, you cannot get those messages back. Backup is scheduled for 4 A.M so it will back up all the message what was in your phone till 4 A.M. If you are planning to format your phone and thinking that messages are saved in Google Drive. Then you are wrong. Backup only restore a backup from phone memory. For latest backup, create a manual backup on your phone. Copy the backup file to SD card or keep on google drive manually before formatting your phone. It is possible that you are unable to restore your backup if your backup file is corrupt.