Was trying to change the ownership of a folder but executed this command
email@example.com:~# chown -R www-data:www-data /
The entire directory structure under '/' got changed. Upon realising the mistake I executed this command
firstname.lastname@example.org:~# chown -R root:root /
Now I am unable to execute php scripts as apache user. Mysql is unable to find an existing database (shows 'unknown database'). Not sure what else got broken.