Website Hacked, how do l secure now

A website l was working on got hacked.. I realized l am having a lot of traffic, lots of comments like 2million comments.. Now the website is refusing to open... It says cannot connect to mysql error

This is the ip adddress after looking it up and the same ip has accessed the website more than million times

General IP Information

IP: 198.15.126.165 and 212.124.115.154
Decimal: 3322904229
Hostname: 198.15.126.165
ISP: Secured Servers LLC
Organization: Secured Servers LLC
Services: None detected
Type: Corporate
Assignment: Static IP
Blacklist:
Geolocation Information

Country: United States
State/Region: Arizona
City: Tempe
Latitude: 33.4357 (33° 26′ 8.52″ N)
Longitude: -111.9171 (111° 55′ 1.56″ W)
Area Code: 480
Postal Code: 85281

How do l solve this issue and prevent it from happening?

A website l was working on got hacked.. I realized l am having a lot of traffic, lots of comments like 2million comments..

I think its not hacked..... maybe your company closed your site bcs much trafic and files....and you got much comment via spam....
Install captcha into your site, for comments, guestbook and user/register..... that can close your problem..... send a url from your site....