Please help, been hacked & thrown out my site!

Hi,

I know nothing about IT at all but run a blog at https://www.thebeautyobsession.com at lunchtime today I recieved an email to say that a new user had been set up on the site. I went straight into the site, deleted the user from the admin panel and changed all the passwords. Now tonight I’ve had another new user notification:
Username: dfonis5

E-mail: [email protected]

Except now I can’t get into the dashboard as admin at all, the password seems to have been changed and if I ask for a reset, it doesnt send it to my email address, so that must have been changed too.

Please can someone advise what I should do, so upset!

Many Thanks,
S