How do I determine which version of Ubuntu I am using?

1. From the desktop, select: Applications > Accessories > Terminal. A command-line terminal window will open.
2. At the terminal prompt, type: lsb_release -a then press Enter.
   
3. Information about your installation will be displayed.
   

Rhythmbox stopped playing my MP3s. How do I fix it?

1. Select: System > Preferences > Sound.
2. Set all Sound Playback dropdowns to: ALSA - Advanced Linux Sound Architecture.
3. Click: Close.
4. Exit Rhythmbox by selecting: File > Quit.
5. Launch Rhythmbox.