Hi,
yesterday i noticed a page of my website was "unformatted", checking with chrome i realized the k2.css was not loaded.
The error in chrome inspects was:

GET www.gamazine.it/components/com_k2/css/k2.css 404 (View not found [name, type, prefix]: category, css, contentView)
224-dead-or-alive-xtreme-3-hitomi-trailer.html:39 GET www.gamazine.it/components/com_k2/js/k2.js?v2.6.9&sitepath=/ 404 (View not found [name, type, prefix]: category, js, contentView)
224-dead-or-alive-xtreme-3-hitomi-trailer.html:378 Uncaught SyntaxError: Unexpected token ILLEGAL

This error was found on only one page.
I did several tests including:
delete cache
disable cache, gzip
disable and uninstall Jotcache
disable and uninstall JCH optimizer
copy the files in /com_k2/templates to the folder /templates/miotemplate/html/com_k2/
change the permission to the cache folder from 755 to 775
copy the k2.css file in the folder /templates/my-template/css/custom/

every single change, i deleted the cache before refresh, and checked the website with either chrome and firefox.
The only result is that now the other pages are not displayed correctly (whereas before it was just one)
Then I tried to restore everything, i reinstalled JCH and put back the settings as they were before, rehabilitating gzip and cache.
when i try to open the url website.it/components/com_k2/css/k2.css on my brower i get a 404 page...

My website is gamazine .it
All the pages of the items were formatted correctly by K2, now are not anymore.
The page that initially does not see properly was: gamazine .it/blog/
My htaccess file have one redirect (from non-www to www), the rest is the joomla default htaccess
recently i added the cloudflare service but i never noticed if that page had already before these errors
on cloudflare i disabled the minify options but the cache cannot be disabled

Joomla version v3.4.8 stable
K2 version 2.6.9
Php 5.4.39
The template is Xenon from Rockettheme
Extensions used: Jotcache and JCH optimize (free)

I hope I have said everything.
I don't have more ideas on how to fix this error, I hope someone can help me because the site as well is unusable

Thank you

Are you using any 3rd party SEO extensions?

Thank you for answer me.
yes, only RSseo.
The sef is enabled by joomla default options, i don't have any sef extension installed.

Can you disable the SEO extension and try again?
If you are also using an edited htaccess site, please revert temporarily to the default one.

Ok i disabled RSseo, Jotcache, JCH optimize and restored the original htaccess, but i still get the same error..

OH! I solved this problem by accident!
i was checking the files/folders and i noticed the /css/ folder was having wrong permissions (744)
I changed to 755 and now everything works perfectly!
I don't know how this folder changed the permissions.. i never touched it...
Thank you for the support!

You 're welcome Francesco,
Thank you for sharing the culprit.