Question about vbulletin install script

[MrHorror]

So an accidental installation of a vb4 mod on a vb3 board has thrown our board a bit out of lineage as far as styles are concerned. And the way they look. So I have a question about reinstalling vb from scratch.

I have a forums folder that has all of my stuff in it for nivo slider, our forum app, etc. If I were to reupload the vbulletin install script, run it. And then import our .sql database, would that solve the problem? And would everything be intact such as our styles? I know posts and stuff would still be there. But as far as styles and designs are concerned? Keep in mind our styles are self-designed. We didn't upload any designer skins or anything. And what exactly does the install script do as far as rebuilding vb structure and look that might have been mis-shapen due to a bad plugin?