If it was not a new install I would suggest crashed tables but my guess is an ODBC problem (missing libraries, etc…) or incorrect user/password/database.
As far as config is concerned I would look into /etc/odbc.ini and /etc/asterisk/res_odbc_additional.conf (this one is under the control of FreePBX, you should not modify it directly. If needed this can be changed under advanced settings.
There are also references to the database in /etc/asterisk/cdr_adaptive_odbc.conf…
Your logs should give you some clue about what is going wrong (missing dependency, bad password, etc…) when you place/receive calls…
La revedere!
(Once again please forgive me if I am wrong about this…)