How can I restore /etc/nginx? [closed]

To recreate it, first uninstall using purge to remove even configuration files and records:

sudo apt-get purge nginx nginx-common nginx-full

then reinstall:

sudo apt-get install nginx

If above doesn't work for you, you can also try using --force-confmiss option of dpkg.

sudo dpkg --force-confmiss -i /var/cache/apt/archives/nginx-common_*.deb