From Help system
Regenerate SSL for PPP
vzctl enter 1
su -
cd /etc/httpd/conf
mkdir backup
cp -ra ssl.* backup/
rm -f ssl.*/*
/usr/bin/openssl genrsa 1024 > /etc/httpd/conf/ssl.key/server.key
chmod go-rwx /etc/httpd/conf/ssl.key/server.key
make testcert
/etc/init.d/vzcp restart