Indeed, it's possible you can do so without having recourse to anything more difficult than restoring from backup - we recommend iTunes. And at worst you may be able to get those messages back using a third-party app.
If you've got the the opposite problem, we've also got a guide on how to delete all messages on an iPhone. And, just in case you didn't know, you can send group texts from Android and iPhone.
iCloud
If you have ever backed up your iPhone to iCloud or iTunes you should be able to restore your iPhone text messages from the backup.
Unfortunately, iCloud doesn't back up texts in all territories, and for all phone operators. My iPhone on O2 falls into this category. So the following may not work. You'll need only to go to step 2 to find out.
- Log in to https://icloud.com with your Apple ID and password
- Click on Text Messages (if it isn't there your messages haven't been backed up).
- If it is there searched the messages to find the ones you need.
- Now go to your iPhone and choose Settings, iCloud on your iPhone.
- Turn off Text Messages (or ensure it is turned off). I know this sounds counter-intuitive but stay with it.
- You'll see a pop-up. Select: 'Keep on My iPhone'.
- Now turn back on text messages.
- Tap 'Merge', and wait. After a few minutes the deleted text messages should appear back on your iPhone.
You can also try restoring your iPhone to an iCloud backup, should you have one from before the text messages were deleted. Check in Settings > [Your Name] > iCloud > Manage Storage > Backups.
If you do, then you can factory reset your iPhone before restoring it via that iCloud backup, if you have one. Note that the last successful iCloud backup time/date is available beneath the Back Up Now button.
iTunes
Don't worry if iCloud didn't work. We have two further options to try. First let's try recovering deleted text messages via an iTunes backup. This can often be the best way.
Unless you disabled the automatic sync option in iTunes, you should have created a backup everytime you synched with your PC or Mac.
- Connect your iPhone to the PC with which you sync it. iTunes should open (if not, open it manually)
- You should see your iPhone appear. Select it
- Now choose 'Restore backup'
- All the data you previously backed up will now replace the data on your phone. It will take a few minutes. As long as you haven't backed up subsequent to deleting those messages, they should now appear on your phone.
Third-Party App
If neither of the options above has worked, it is time to go nuclear. Well, not nuclear exactly but it may cost you a couple of quid, and there is no guarantee it will work.
We've never used any of these, but a there are some third-party apps appear to have a good online reputation: PhoneRescue by iMobie, Enigma Recovery, WonderShare Dr.Fone for iOS, iMyFone D-Back Data Recovery and Tenorshare iPhone Data Recovery.
Because even after you have 'deleted' messages they remain on your handset until overwritten, you should be able to recover deleted messages using these utilities (and others) - but there are no guarantees.