How can retrieve the photos in my iphone which data is erased

If you had iCloud Photos turned on, log into www.icloud.com and go to the Photos app there. If you turn on iCloud Photos in a device, those photos will sync with it. See: Set up and use iCloud Photos - Apple Support

If you didn't have iCloud Photos turned on but do have an iCloud backup, you can restore the entire phone (not just the photos) from iCloud but you cannot otherwise view the contents of the backup. The following Apple article has information about backup: Restore your iPhone, iPad, or iPod touch from a backup - Apple Support