This tutorial is applicable for only Parallels Plesk Panel 10.x for Linux
If you need to quickly re-establish contents of /var/www/vhosts/ folder for all clients without restoring full backup. Then you need to find contents of the mentioned folders that located in dumps folder by using the following technique.
# grep DUMP_D /etc/psa/psa.conf
Generally it is located in /var/lib/psa/dumps/clients/<client_login>/domains/<domain_name>/ and has a name like testbackup_domain.com_vhost_1207281225.tgz