The first thing I would do is change host , change db passwords, and check the write permissions on files.
Then I would also check my computer for any viruses , but just format it to be sure. When I was first starting I got your problem and I found out that they also hacked my PC, and the website .
You don't need any backup buddy, just download your database, and upload it to the new host. Then edit it in phpmyadmin if there are any problems left. But I would look for another username created in there. because sometimes they create another user in wordpress.