If you want to reset the permissions on the files and directories on a hosted site, the following shell commands may be useful:
YourPrompt$ find /home/public -type d -exec chmod 755 {} \;
YourPrompt$ find /home/public -type f -exec chmod 644 {} \;
This will reset your files and directories to the default permissions our system would assign them under ordinary circumstances.
It will not help if files or directories are (or should be) owned by the web user.