By default a Fedora Linux does not support playing MP3 files. The same must then apply also for an Amarok music player. To enable MP3 support a user needs to install non-free codec. First add rmpfusion repositories:
NOTE: the command below will enable both free and non-free rmpfusion repositories
$ su -c 'yum localinstall --nogpgcheck \ http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-stable.noarch.rpm \ http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-stable.noarch.rpm'
Once you have included rpmfusion repositories navigate to:
Amarok -> Settings -> Configure Amarok -> Playback -> Configure Phonon -> Backend (tab ) .
Clicking on the backend tab you should see what sound system you are using. In case you are using Xine add MP3 supprot by installing a xine-lib-extras-freeworld package:
# yum install xine-lib-extras-freeworld
For those using GStreamer enable Amarok MP3 support by installing a gstreamer-plugins-ugly
# yum install gstreamer-plugins-ugly