If amarok not start test it in a konsole:

$> amarok

if you have this:

$ amarok
amaroK: [Loader] Starting amarokapp..
amaroK: [Loader] Don\'t run gdb, valgrind, etc. against this binary! Use amarokapp.
QLayout: Adding KToolBar/mainToolBar (child of QVBox/unnamed) to layout for PlaylistWindow/PlaylistWindow
SWFDEC: ERROR: swfdec_font.c(158): tag_func_define_font_2: langcode 1


You can fix the problem uninstalling the package:

libswfdec0.3
SWF (Macromedia Flash) decoder library

And Play your music now!