Have you accidentally deleted some important threads from WhatsApp, tried to recover them using some commercially available software to recover deleted files from mobile phones but had no luck? Sorry, but these types of solutions only work with photos, videos and a few other types of files, not with WhatsApp messages.
If you want to recover deleted WhatsApp messages, the only solution available to you is to reinstall the application and follow the standard procedure to restore the last backup made by the application.
As you probably already know, WhatsApp automatically generates backup copies of all chats. It does this on a daily, weekly, or monthly basis (depending on your preferences) and using one of these backups you can restore all those conversations that now seem lost forever. Of course, if you return WhatsApp to a previous state, you will lose all messages received or sent after the backup date... but at this point I think other messages have a higher priority, right? So let's ban the chitchat and see how to restore all the chats you deleted by mistake.
Retrieve deleted WhatsApp messages from Android
The Android version of WhatsApp saves chat backups both locally, on your smartphone's memory, and online on Google Drive. The restore procedure is the same in both cases, all you need to do is remove WhatsApp from your smartphone (press and hold its icon and drag it to the trash can or go to the Settings > App > WhatsApp menu), download it again from the Play Store, and follow the application's initial setup procedure.
After checking the number, the app will automatically detect the presence of a backup and ask the user whether to restore it. At that point, all you have to do is press the Restore button and all the conversations will be restored to the state they were on the backup date (so messages deleted by mistake will be restored automatically).
If you don't know when WhatsApp's last automatically generated backup occurred, open the application on your smartphone, press the (...) button in the upper right corner, and select Settings from the menu that appears. On the screen that opens, select Chat > Chat Backup and check the dates listed under Last Backup. There should be both the date of the last backup made locally and the date of the last backup saved online on Google Drive.
Now, if the last backup made on Google Drive is later than the date you deleted the messages you now want to restore, uninstall the app from your phone, reinstall it and choose to restore the backup from Google Drive: all the messages you are interested in will be restored automatically (except those received after the backup date). If the date of the last backup on Google Drive is after the deletion of the messages you are interested in, you have to go to "plan B", i.e. restore local backups.
Using locally saved backups, you can also restore the status of the application to a date earlier than the date of the last automatic backup. All you need to do is go into the folder where WhatsApp stores its backup files, locate the date you want to report the status of the conversations and rename it so that the application considers it the most recent backup to restore.
To be more precise, what you need to do is install a file manager like ES File Manager and use it to enter the HomeWhatsAppDatabases folder on your smartphone or sdcardWhatsAppDatabases if you use a microSD for memory expansion: there you will find a series of files called msgstore-[data].1.db.crypt12 where instead of [date] there is the date when the backup was generated.
If you don't know how to get to the location I just indicated, press the burger icon located at the top left of the ES File Manager home screen, select the home or SD card icon from the left sidebar and go first to the WhatsApp folder and then to the Databases folder.
Now, locate the backup file to use in WhatsApp and rename it to msgstore.db.crypt12. If a file with the same name is already inside the folder (it should be the most recent backup generated by the application), delete it or rename it another way. To rename or delete a file with ES File Manager, just keep your finger pressed on its icon and press the appropriate button at the bottom.
When you are done, you can remove WhatsApp from your smartphone. If a message from ES File Explorer appears after uninstalling the application from your phone asking if you want to delete the remaining WhatsApp Messenger files from your smartphone, reject it, otherwise the backup you need to restore will also be deleted.
Now, before you reinstall WhatsApp and restore chat, remove the association between Google Drive and WhatsApp. This way, the application will search for backups directly on your phone's memory and will not attempt to restore conversations from the cloud. To do this, open Google Settings (the gear icon located on the screen with the list of apps installed on your phone), select the Connected Apps item from the screen that opens and press the WhatsApp icon first and then the Disconnect button. Alternatively, log in to this web page and delete WhatsApp from the apps associated with your Google account.
That's it! Now open the Play Store, reinstall WhatsApp Messenger, follow the application's initial setup process and accept the restore of the backup you renamed earlier. If all goes well, you will be able to restore WhatsApp to the date you want and restore the messages you deleted by mistake.
Retrieve deleted WhatsApp messages from iPhone
On iPhone, you can restore WhatsApp backups only through iCloud, Apple's cloud storage service, so you can't choose the date to report the status of your conversations and you can only restore the most recent backup from the application. To verify the date of WhatsApp's last backup, open the application, select the Settings tab at the bottom right and move to Chat > Chat Backup.
The restore procedure is identical to the one we just saw for Android terminals: you have to uninstall the application from your phone (keeping your finger pressed on its icon and pressing on the "x" that appears in the top left corner) and reinstall it through the App Store. Then you have to follow the initial configuration procedure of the app and accept the restore of the backup, which will be automatically detected thanks to iCloud.
In the unfortunate event that the iCloud backup was later than the date you deleted the messages you want to restore, you can completely reset the iPhone and restore it via an iTunes or iCloud backup. This is quite drastic and uncertain, but it's the only hope to recover lost WhatsApp conversations.
To make sure everything goes smoothly, make sure your iTunes/iCloud backup is prior to the date you deleted WhatsApp retrieve messages (but not too old either, otherwise you'd risk losing a lot of recent chats). If you don't know how to restore an iPhone using iTunes or iCloud backups.
Retrieve deleted WhatsApp messages from Windows Phone
Windows Phone also allows you to restore WhatsApp messages from previous backups, but does not currently support cloud services (messages are saved locally to the phone memory or microSD). If you have a phone equipped with Microsoft's operating system and want to verify the date of the last backup, launch the application, press the (...) button at the bottom right and select Settings from the menu that appears. On the screen that opens, select the Chat item and check the date indicated under Backup.
If the backup date is earlier than the day you deleted the messages you want to restore, uninstall WhatsApp from your smartphone (keep your finger pressed on its icon and select Remove from the menu that appears) and download the application from the Windows Phone Store again.
When installation is complete, launch WhatsApp, follow the application setup wizard, and after verifying the number, click the Restore button to restore the message backup.