What would you do is someone hijacked your site and requested payment to get it back?

[BrolySSJ]

We shouldn't encourage hackers, by paying them. Contact your hosting company to help you with this. Would advise you to temporarily shut down the website and clear all the data and build it from the ground up. And use this experience to create solid security for the new website.

There are many companies that will actually hire a hacker in order to pay them and get them to show them where their system is vulnerable and therefore that can be quite useful.