How to make a "clean" reinstallation

[stamat]

Hello everybody.
Can someone help me how to do a clean reinstallation ?

What i want to do ?

I want to keep users, forum threads, posts, pms etc... and i don't want to keep ANY hack, modification, style etc.

I want the source code to be new one but the "main" forum to be moved.
How can i do that ?

[Zachery]

Uninstall your hacks, delete all of your styles and add a new default one, reupload the default vBulletin files, :)