In order for you to be able to recreate deleted messages at all, your iPhone needs to use at least IOS 16, while your iPad needs to run Ipad OS 16.1 or later.
Another thing to keep in mind is that you can only recover messages and conversations that you deleted in the last 30 to 40 days. You also can’t recover a message that was deleted before you updated iOS 16/Ipad OS 16 – it will remain deleted, unless you have a backup of your phone.
Read also: How to organize your notifications in iPhone
If you are running iOS 16 or higher, you can easily recover deleted messages by doing the following:
1. Open the Messages app on your iPhone or iPad and press Change top left corner.

2. Tap on Show last deleted.

3. Select which conversations you want to recreate, then tap Recreate.

4. Done!