My forum was until recently hosted on a free forum creation website. I wanted to upgrade and host it on my own server so they e-mailed me the database as a .sql. The forum was PHPbb2. I have installed a clean PHPBB2 on my server, uploaded the database I was sent and merged it with a new database using big dump. However, when I visit the forum on my server I don't see any of the posts and users from my backup. This is really important to me and I will pay $20 paypal to anyone who can get my new forum working with all the old posts and users.
You's have to give someone your login and password to the hosting account to get that done. This isn't overly difficult, but the person could hijack your account. Check the database (use phpMyAdmin) and see if there are any links in it pointing to your old site. You'll have to change them to point to your new site.