I\'m working on a site which I havent coded from scratch and in firebug the css files are being displayed as: style.css.pagespeed.ce.5d2Z68nynm.css with the pagespeed extens
Another option for resetting the cache is described here:
Find out where is the cache folder, it's defined in the config file under ModPagespeedFileCachePath property.
Then run the following command from shell:
touch /cache.flush
(In my case: touch /var/cache/mod_pagespeed/cache.flush)
That's it. The cache was reset.