You can reset file permissions via PHP. the code below is an example on resetting file permission recursively. You must have shell_exec enabled.

• Create a blank php file
• Add the following code to it

  <?php
    echo shell_exec( 'find . -type f -print0 | xargs -0 chmod 644' );
    echo shell_exec( 'find . -type d -print0 | xargs -0 chmod 755' );
  ?>

• Place the file in the root directory you want it to work from
• go to your webbrowser and execute the file