Hello,
It appears your website has been compromised. Whether it has been logged into by someone other than yourself and then been tampered with, or whether it's been exploited due to a poorly coded script or application or even an outdated script or application.
From here there are a couple of options, we can either wipe the account clean of all files, you start fresh and ensure all scripts are fully up to date, and reset your password to a new one to ensure account security. Alternatively we may be able to provide all of the files to you in which case you would have your files, but I highly recommend against this as the website has already been compromised and it's near impossible to ensure 100% security again without a clean re-install of whatever you had on your site.