[ubuntu]reinstall apache2 and can not access to my wordpress

my wordpress folder is in the /var/www/html/

so the first time I want to locate the domain name to /var/www/html/wordpress but I lost the css, and I don’t know why.

Then I found some files of apaches deleted by me so I tried to reinstall apache2 by using this command:

sudo apt-get purge apache2 apache2-utils apache2.2-bin apache2-common
sudo apt-get autoremove --purge
whereis apache2

Then I delete all the files concerned with whereis apache2 and sudo apt-get install apache2

Then the question is:

when I visit the IP address of my vps, chrome tells me that the website is not available, and to the domain name it shows the apache2 ubuntu default page.

So please tell me what should I do right now to fix this?
If there is no way to fix it please tell me how to back my wordpress up.

Thank you.