I seem to be missing the Wpdmtp.inf file on my computer, and so it can't load portable device drivers. How can I fix that?

Trying to install my Zune on my work computer. The drivers and everything are up to date but Device Manager says it’s not working properly, giving Code 31, that says Windows can’t load the necessary drivers for the device. I looked into it further, and it says this could happen if the Wpdmtp.inf is missing. How do I fix this?