The website is not available at addressing from www

In this case it shall be necessary to make sure that DNS setting is correct.

In particular, make sure of availability of a record (in the list of A records for your domain name) of the following type:

If DNS is set up correctly and website without WWW operates normally, but at addressing from WWW an error "Account is blocked" or "Domain name not found at hosting" occurs, make sure that a check mark is put against "WWW" (for this domain name) in "Registrant" menu item of Plesk control panel.