Goolge Sites are BLOCKED! Yup, this happens often, you've likely blocked google Cookies!
Open Chrome, click on the 3 dots and then on settings.
2. Click on "Privacy & Security" and then on "Cookies & Other Site Data"
3. Find "Sites that can Never Use Cookies", you likely have Google listed there.
4. Click on REMOVE.
Close your Browser and reopen, your Google sites should be available again!