default music player disappeared on Ubuntu 12.04

[Gelonida N]

Hi,

I installed Ubuntu 12.04 and had a music player installed (by default), 
that I could access via the top bar's audio icon.


I installed now some alternative desk top managers and somehow one of 
the installed packages seems to have removed my audioplayer.

It is now replaced by gmusicbrowser and my playlist of the preceeding 
audio players are of course not used.


So my questions:

1.) What is the daufault audio player on Ubuntu 12.04?
2.) How can I start it if it is no more the defualt player?
3.) What do I have to do to make it again the default player?
4.) Is it possible to have two different audio players in the
      top bar's audio menu?


Thanks in advance for your answers