how can i retrieve deleted text messages

If you had messages in iCloud turned on Keep all your messages in iCloud - Apple Support and those messages were deleted, then they are permanently gone. If that feature wasn't turned on, you can restore from a backup -- Restore your iPhone, iPad, or iPod touch from a backup - Apple Support.

If you’re not using messages in iCloud, they are part of your backup until the next backup replaces the backup and reflects the changes. So unless you only deleted these fairly recently, they won’t even be in your iCloud backup any longer.