Suddenly lost all styling

I am using 3.50.  I have been running it on my local PC for weeks and web pages display with all normal styling.  I published a few days ago to a server and all web pages were also displaying correctly.  Now, all styling has been lost.  I can see all the links and such but there is no styling at all.  Nothing has changed on this server.  Why would this suddenly start occurring?

I don't know if it can help, but you could verify what account is associated to your anonymous authentification in IIS, and check if this account have read access to your application folder.
Regards

Thanks for the reply.  How do I check this account?  Sorry, our network guy left recently and I'm more of a developer.

nicolas,

You were right.  Someone on our end changed the permissions of the anonymous user.  I changed it back and it now works again.

Thanks for your help!