recover deleted text messages

If you sync messages with iCloud, when you delete them they are gone.

If you don't sync messages with iCloud and you have a backup made before you deleted the messages, you can restore from that backup, BUT your phone will be restored to the date the backup was made, so messages sent or received after that date will be gone.

If the messages are still on your iPad and your iPad and your iPhone are on the same Apple ID, go to settings on your iPad > Your Name, iCloud, iTunes and App Store > iCloud and then turn on Messages there.

Then give your iPad time for the messages to sync with iCloud.

Then go do the same on your iPhone and your messages will sync from iCloud to your iPhone and they'll be restores to your iPhone.

Once you are syncing messages across your iPad and iPhone, it's important to recognize that if you delete a message on any device, they will delete on all devices sharing the same Apple ID. Be careful when you delete messages.

It's very unfortunate you didn't take my advice, which would have absolutely restored the messages back to your iPhone.

You said in the post above the messages are now gone from your iPad and iPhone? In order to restore the backup, you'd have to restore an iPad backup to your iPhone. You can do that, but you're going to lose things you have on your iPhone that are not in the iPad backup. And it's now possible your iPad backup no longer contains the messages.

Your son really messed you up unfortunately.