There are two challenges: finding and removing the damage/redirect, and then locating and closing the attack vector.
Many suggest that the best approach is to restore the site files + database from a clean backup (in this case before 02/07) and then change all passwords and add new salt keys. But then you would still need to identify how the attacker got in. Common vulnerabilities are in outdated plugins/themes/core or 3rd party plugins/themes.
If you don't have a clean backup then try installing and scanning with Wordfence and/or GOTMLS, check your .htaccess file in the root for redirect code, index.php, header.php. Scan the site files and database for the site url and/or IP address, look in database for new unknown admin accounts. If it's not a sophisticated attack you may strike lucky. If not you may need professional help: google hack repair or post for help in http://jobs.wordpress.net/
Good luck!