How to recover deleted messages on iPhone?

Assuming that you have installed iOS 16 on the phone.......

Open the Messages app

Tap on Edit

Tap on Show Recently Deleted

Messages that have been deleted within the last 30 days will appear, so you can restore those messages. Messages that were deleted more than 30 days ago have already been permanently deleted and cannot be recovered.

neicca Said:

"Text messages: How do I get old messages back on to my phone"

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Recovering Deleted Messages:

What to Consider:

A. Restore from Today's Backup:

Restore your iPhone from a backup of it that contains these messages, and you could recover them. Note: To restore, it would have to be of the same iOS version.

B. Check Messages App:

If messages was enabled on your iPhone along with your Apple computer, then check and see if the Messages app is enabled on your Mac to see if it exists in it. You'd start up your Mac, not connecting to the Internet, and open the Massages app. Then proceed from there with retrieving it. Important: Be certain you do not connect to the Internet while booting up, as syncing would delete it. So, power off your router to avoid the connection.

C.  Check your Carrier’s Site:

Log in to your Carrier’s site, seeing if you can view a history there. Doing so, I can see a call log going back 90 days —but not a text messages log.

See this article.

Recover deleted messages on iPhone - Apple Support