What theme and plugins were you using?
Were you keeping everything up to date?
Ideally restore from a known pre-hack backup. Do you have daily backups in place with your host?
If you can't, make sure your WP core, theme and plugins are all up to date.
Download WordFence and run their scan. This should detect any altered core files and will hopefully find obvious unexpected files inserted by the hacker.
You can install Seccuri and run the post hack checks it has.
You'll also want to check for any new unauthourised admin accounts, you'll want to check the database for any hidden admin accounts too, that may have been altered so they don't show up in the control panel.
You might want to search your files and the database for any unexpectured use of the eval() function
Check for any backdoors
https://www.wordfence.com/learn/finding-removing-backdoors/
Check for any new plugins that you didn't install.
It's worth following the Wordfence blog and subscribing to their newletter to get notified of any major exploits.
If you don't need a dynamic wordpress site, definitely consider going down the static route or use a tool to create a fresh static version of the site you built in WP and start from scratch.