vicidial.org

I have a vicibox redux 4.0.3 installed at my place. Last day I saw all table datatypes are changed & all numbers are replaced by a single number, also mysql password changed. I suspect a possible hack attack. I cannot find any logs on the server. I am a beginner, need help.

Yeah sounds like an attack,
logs are located at /var/log/
/var/log/apache2/access_log is probably what you want to look in.

is the server accessible to the internet? then fix that, these servers aren't meant to be on the internet.
you should probably consider paying someone to solve your issue if you're a beginner.

could be you are using default passwords for cron and custom mysql users