I have had two WordPress blogs. That was in a time when I was doing almost no internet advertising, and until I found time to handle the situation (weeks later), these sites were penalized at the main search engines. They were not eliminated the ratings were reduced.
Since scare tactics appear to be what drives some people to take how to fix hacked wordpress site a little more seriously, or at least start considering the problem, let me shoot a scare tactics your way.
Basically, it all will start with the fundamentals. Try to use passwords. Use spaces, numbers, special characters, and letters and combine them to make a password that is special. You could also use usernames that aren't obvious.
You must create a user, before you can delete the default admin account. To do this go to your WordPress Dashboard and click on User -> Create New User. Then enter all reference the information you need to enter.
You can create a firewall that blocks hackers. The firewall prevents the hacker. You also have to have updated version of Apache. Upgrade your PHP as official website well. It's essential that your system is always filled with upgrades.
Do your homework and some hunting, but if you are pressed for time and want to get this done once and for all, try out the WordPress safety plugin that I use. this post It's a relief to know that my website (and company!) are secure.