In the future, if you are having problems with a debian package there are three standard steps you should take (each more drastic than the last). In these examples, replace <package> with the package name.
1. dpkg-reconfigure <package>
This will reconfigure the package, and ask you the configuration questions about the package again. With the PHP modules, it will check the php.ini files, and make sure that it is properly installed in each one of them.
2. apt-get --reinstall install <package>
This will reinstall the package, downloading it if necessary, and unpacking and installing just as if you were upgrading to that version.
3. dpkg --purge <package> ; apt-get install <package>
CAUTION: This will remove all configuration files for this package. Any custom modifications to the configuration files will be destroyed. This will totally remove, and then reinstall the package. Only use this as a last-case resort, because you will also have to remove all packages that depend on the package you are reinstalling.