Always the permission of folders and files must be set because of the security reasons.

To change all the directories to 755 (-rwxr-xr-x):

find /home/user_name/public_html -type d -exec chmod 555 {} \;

To change all the files to 644 (-rw-r–r–):

find /home/user_name/public_html -type f -exec chmod 444 {} \;