Moved HTTP root directory… need help with WP now

I used to have only WP running on my home HTTP server and the root home directory was set to <http dir>\blog

However now I’m running a few additional sites and such so I moved the home HTTP dir to just <http dir>\

As you can imagine this screwd up my WP install. Is there a way to repoint the WP install so it sees its home directory as the \blog?

Please help and thanks!