Unless your using Frontpage Extensions then I would recommend you uninstall them. If you've already removed your wordpress then delete your .htaccess file and your site should start working again. But installing wordpress again is just going to add to your .htaccess file what is giving you the 500 error. If you'll post what's being added by wordpress I can show you what to delete.
I can't reset your site, all I can do is delete it and you can re-register.