You could try reinstalling WMP9 over itself. Look for a file called setup_wm (usually in \Program Files\Windows Media Player) & double-click it to bring up the setup wizard. Follow the wizard to reinstall.
Note: Even if it works, WMP9 will by default only burn CDs at a 2x speed (which is very slow). You'd be better off burning with ECDC4 & your CD-writer as you'll probably get a faster burn speed (dependent on your CD-writer burn speed(s) & the blank media, of course). G