Guide To Error 8007007E In Windows Media Player
Error 8007007E or "Module not found" means something in the playback chain isn't fully installed. It is most likely not WMP, but something like a sound card driver. http://www.zachd.com/pss/pss.html#isolate may help narrow it down a bit. Basically you are looking for what works and what doesn't, then you can find out what is not installed or what is broken.
There is not a single solution to this problem. Your answer will depend on what exactly doesn't work. DirectX, third party codec's, sound card drivers, video card drivers, and many other things can cause this.