website hacked, can't even login

Hi,
My website has been hack. Currently, I can’t even go to the login page for my wordpress, so i can’t login to check what’s happening. The page that appear is a cash advance / credit website that is clearly not my professionnal domain.

I’ve change my gmail password and my Justhost password just in case. It seems to me that they have my password for my wordpress.

I’ve tried to update my WordPress via Justhost, but even then it doesn’t change anything.

I’ve paid my account in august, so it can’t be that I’ve lost my «domain name».

Since I am not that good with internet/computer stuff, I really hope that you can help me.

I’m sorry for the quality of my writhing in english, it is not my first tongue. I hope I’ve explain my situation well.

I have no idea what to do. I’ve read some suggestion, but the ones I’ve found all include that I can enter my WordPress, which is not the case.

I clearly don’t know what to do to recover my website.

Thank you!