When image styles are aplied to images the modified images are not created and the image url returns a 404 error. I've been checking for solutions and none worked for me. I commented the Options +FollowSymLinks in the .htaccess (https://www.drupal.org/node/1170440), I changed the files folder permissions to 777, I changed the theme and back... (image style (imagecache) images are not being created), and still nothing.
The worst part is that it was working fine until yesterday (at least i found it yesterday) and many of the pictures have their modified versions working, but not the new ones for which the url returns de 404.
Is there any thing I can do that I've not tried yet?