Where can I find a music player for my PC that plays ALL music file types?

Answer 1

http://www.winamp.com/

Answer 2

Your player will play all types, you just have to set it to do so.

For Windows Media Player (10)
Open WMP
Right click on Music
Select Options from the drop down menu
Select the tab that says "file types"
Click on "Select All"
Click Apply
Close and restart your computer.