Retrieving old text messages on an iPhone can be important for holding onto memories or important information. One way to do this is by using iCloud Backup, where messages can be restored if they were included in a backup made before they were deleted. Have you tried accessing your iCloud account to check for backups? Another option is to use third-party recovery software. Do you remember if you had iCloud backup enabled on your iPhone? Let me know if you need further assistance!