How to restore deleted iMessages?

go to Settings > [your name] > iCloud and check the switch position for Messages

If the switch is ON, then you cannot recover your deleted messages (no need to read any further)

If the switch is OFF, then you might be able to recover your messages IF you have an iPhone backup that contains the messages you are trying to recover. In which case you'd need to restore your iPhone to that backup. In doing so, you'd likely lose some data between now and whenever your backup occurred.

Locate backups of your iPhone, iPad, and iPod touch - Apple Support

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

In theory.. If you have an iPhone backup prior to turning that switch on, then your text messages should be contained in an iPhone backup.

Do you have a recent iPhone backup that's new enough to contain the text messages you are trying to restore?

If you have such a backup, you'd have to restore your entire phone. You can't just extract the messages.

If a new backup occurred after you turned on the switch, then your messages are most likely gone.

I believe the thread should be there then..

About backups for iPhone, iPad, and iPod touch - Apple Support

Maybe turn that switch back off before restoring.

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

here is a link from my original post that talks about how to find your backups. Hopefully you are able to find it

Locate backups of your iPhone, iPad, and iPod touch - Apple Support