Document contents are stored in the file system directly. Backup and restore of just mysql is not sufficient to restore.
If the original site has not been deleted already the contents from /var/www/openemr/sites/sitename/documents can be copied using the ‘cp’ command to the new directory. If moving from an old machine to a new machine a different method for moving the files will be needed such as creating an archive and moving it or using sftp.