Which file is needed

"Hariharasubhramanya Viradiyar" <[email protected]> Fri, 2 Jun 2006 19:18:24 +0530
Newsgroups gmane.org.region.india.fsug-kochi
Message-ID <[email protected]>
Which file is needed for making my system [Ubuntu distro] to play
1.mp3
2.dat [video files]
3.mpeg

I am a doctor by profession,new to computer and kid on linux it will
be nice if you give the exact files than providing the links.