Job for nginx.service failed because the control process exited with error code. See “systemctl status nginx.service” and “journalctl -xe” for details.
May be apache is started by default, so when you are trying to run the nginx you are getting this exception, may be try to kill the existing 80 & 443 ports and try once,
sudo fuser -k 443/tcp
sudo fuser -k 80/tcp
sudo service nginx restart