I highly doubt the problem is drivers. Windows doesn't need drivers for DVD drives.
The problem most likely is no dvd decoder.
You are going to need to install the dvd player software that came with your drive. After that WMP will be able to play the dvd.
Also just a week or so ago someone asked where to get a 'free dvd player' or something like that, and they were actually looking for a decoder. Someone responded with a codec dl link and that worked for them. Use the search feature and I bet you can find it.
Also btw - don't double post, I deleted your other one.