Not able to send media file via WhatsApp I recently downloaded the CyanogenMod on my Galaxy S2 but I'm not able to send any music files via WhatsApp does anyone have a solution to this problem ??

The error message is "your music player does not support this option try with Android music player"
The music player that comes with CyanogenMod doesn't support selecting the music file to send.  As you mentioned in the comments, custom ROMs may prevent the use of some features, and in this case, sending music files doesn't work.

You could try another custom ROM or reverting back to the stock ROM to enable this feature.