can we play .mp3 format songs in ubuntu

Install ubuntu-restricted-extras. Connect to the internet. In a terminal input: sudo apt-get install ubuntu-restricted-extras

https://help.ubuntu.com/community/RestrictedFormats should have all the info you may need

Play mp3 and dvd under Ubuntu

First please install https://help.ubuntu.com/community/RestrictedFormats

You need to have extra repositories enabled..

Please first enable the multiverse repository:

Open System → Administration → Software sources → [ Tab Ubuntu software ]
enable "Software restrictecd by copyright or legal issue ( multiverse )"
Close and confirm the repository reload.

Type the following command in a terminal (applications → accessories → terminal)

sudo aptitude install vlc

To get better dvd playback first you need to add the medibuntu http://www.medibuntu.org/ repository to your /etc/apt/sources.list file:
here howto add https://help.ubuntu.com/community/Medibuntu here the medibuntu available software list http://packages.medibuntu.org/

Then to install:

sudo update
sudo aptitude install libdvdread3 libdvdnav4 libdvdcss2

give your user password when requested, you don't see nothing when you type it, then press enter.

Hope this helps