Can I Reinstall ?

[belowthebelt]

I am unsure if this is the proper forum first of all; my sincere apologies if it's not the appropriate location.

I had a coder do some work on my site; said coder has been missing in action for over a month; he made some modifications that I cannot figure out how to undo, I would like to know if it's possible to reinstall the VB software and point it to my database so as not to loose any users or posts?

Thanks for the help, and/or pointing me in the right direction.