Forum hacked: Database affected partially

[Alex Carter]

A friend of mine has had her forum hacked and so far we've managed to establish that though all the forums have been deleted, there are still some posts remaining. It's all slightly confusing to the point that not all the postcounts reflect what they were before the hacking occured.

Anyhow, seeing as it's the forums that have been deleted, and a backup was made in June, I'm confused as to how to go about the problem. I've been trying to upload it (the backup) to a seperate, new database and then was intending on going to change the config file to point to the new database.. I'm a tad scared of messing around with the old database as it still contains some of the old info.

I suppose I'm just looking for someone to tell me if I'm actually doing the right thing or not. And should putting the backup up take a rather substantial amount of time? The file size is about 51,500 KB.