I was bit confuse about design option missing. I found in Content > Configuration . Please change header & footer option from here.

To solve this problem run following commands: 1. php bin/Magento setup:upgrade 2. php bin/Magento setup:static-content:deploy 3. php bin/Magento cache:clean 4. php bin/Magento cache:flush If still exist your problem, please restart your web server. I hope solve this issue.