> I have completely removed my website from the server.
> I do not want to post it on another server at the moment.
There's only three realistic ways you got hacked by this guy:
1)
You used a CMS that was outdated and insecure, and it had a weakness in one of the php files.
2)
During your communications with him offering to buy your site, he sent you an executable file (or a macro document) which you opened and it infected your computer with a trojan/keylogger. Or, you already had a trojan and it was nothing to do with this guy.
3)
He phished you with an email or website, getting you to enter your details into a fake form.
If 1) you never want to put it [the site's scripts] online again. Copy and paste the content into an updated CMS like Wordpress, or a static html site. Also bear in mind that you could have been hacked by someone else; the fact this guy had offered to buy your site recently might have been just a coincidence. Actually, rising in the SERP would attract hacking autobots just as much as it would attract this guy to make an offer, so it's not even really much of a coincidence - your hosting account and/or website was probably being constantly hammered by bots.
If 2), then you still have the trojan/keylogger on your computer. Clean it up before doing anything else. Live and learn.
If 3), that's your own fault. Live and learn again.
Once you've dealt with the consequences of 1) or 2), then get new hosting, install the latest wordpress (and keep it up to date), point your old domain to the new IP, and repost your content. The longer you leave the site offline, the more likely it is that you'll lose your SERP positions. Google's going to freakout due to the change in IP and the new CMS/theme anyway, so don't compound that by waiting longer.
Also, do it because you don't take shit from anyone, and you're not going to be beaten by a small setback like this. There's a hundred people just waiting to screw you over in worse ways than this - your bank manager, your college tutor, your future bosses, your so-called friends, your soon-to-be-ex partner, some random fucking guy who wants your parking space, the junkie who'll rob your apartment in five years time, and yes, even your dentist. You can't hit-back at all these people or get even. So you just have to pick yourself up and let it go.