If you visit e.g. http://mypbx.mydomain.com/admin/config.php?display=cdr
(using https and/or port number if appropriate) do you see a blank page? Does the URL in the address bar change?
Cloud or on site? If on site, physical or virtual? If cloud or virtual, it should be easy to take a snapshot, restore from a backup and analyze the snapshot at your leisure.
FreePBX version? Distro or manually installed? SSH access ok? If not, do you have console access? Is Asterisk running? Processing calls?