WordPress error


I run a site with WP multisite installation and all of a sudden my page stopped working. According to ISP the problem is in WP. I can not access my site from http://www.site.com, but I can get to the main site when I leave the www from the beginning of the url (site.com). But when I try to access my WP-admin panel it asks me for my user and PW normally but when I submit them nothing happens, just a blank white screen and nothings loading. I have not made any changes to the system. My site is http://www.taloninfo.fi, in this case you can only access it from taloninfo.fi. Any suggestions?