Why won't Rhythmbox work?

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http://askubuntu.com – I'm using Ubuntu 12.04 LTS and found out that Rhythmbox won't work-- it keeps saying that it requires plugins but everytime I lookup mp3 plugins it appears that the ones that are all needed are already installed-- what do I do fr. here? Help!!! P.S.: I'm a newbie so any handholding would be deeply appreciated. :) (HowTos)