install something like wamp on your computer.
using ftp, download all the phpbb files from your server.
using phpmyadmin, make a database backup from your server.
in your wamp installation, create a new blank database and them import your database backup to it.
copy all the downloaded phpbb files/folders to your www directory in your wamp installation.
I'm baaaaaccckkkk. still doing work on donation basis. PM your needs.
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