Having successfully installed all the necessary software (centos-7-x86_64+ Webuzo + Apache 2) and having seen that my website is working,
I modified Apache by enabling Mod deflate. (LoadModule deflate_module modules/mod_deflate.so)
In order to be effective I decided to restart Apcahe 2. But As I tried to restart it I got error message. (Error There was an error while performing the operation)
So I decided to restart my VPS. Webuzo panel and my website became totally unreachable. I had to install everything from the beginning. The same situation occurred numbers of times on the same hosting. I tried this on another hosting firm. The result was the same.