@jay4joanna: For clarity, did you change the email address attached to Samsung account? If so, please remove the old account from your Galaxy S8+ and re-add it using your new credentials (if you haven't already done so).
Settings > Accounts and backup > Accounts > Samsung > Remove account
Settings > Accounts and backup > Accounts > Add account > Samsung
Following these step, please try heading to the Gallery app > Tap the 3 dots in the top right > Sync with Samsung Cloud > On. If you're unable to recover your pictures in this manner the please close the Gallery app > Swipe up from your Home Screen > Google folder > Photos, and check here, as you may find an archive of your images has been backed up here.