If you need a quick way to reset your public_html data to 755 for directories and 644 for files, then you can use something like this:
cd /home/user/domains/domain.com/public_html
find . -type d -exec chmod 0755 {} \;
find . -type f -exec chmod 0644 {} \;
If you know that PHP runs as the user and not as “apache”, then you can set php files to 600, for an extra level of security, eg:
find . -type f -name '*.php' -exec chmod 600 {} \;