I installed the MATE desktop using this manual http://www.unixmen.com/linux-tutorials/linux-distributions/linux-distributions4-ubuntu/1975-install-linuxmint12-extensions-mate-a-mgse-in-ubuntu-1110- but now i can't open my Ubuntu Software Center and can't open the settings from the update manager.

I removed mate desktop but it doesn't fix the problem, i also reinstalled the software center, software-properties-gtk and software-properties-common using:
sudo apt-get update; sudo apt-get --purge --reinstall install software-center software-properties-common software-properties-gtk.

But when using this line i get the following error:

Reading package lists... Done                             
Reading package lists... Done
Building dependency tree       
Reading state information... Done  
0 upgraded, 0 newly installed, 3 reinstalled, 0 to remove and 0 not upgraded.  
Need to get 0 B/735 kB of archives.  
After this operation, 0 B of additional disk space will be used.  
(Reading database ... 304824 files and directories currently installed.)  
Preparing to replace software-center 5.0.2 (using .../software-center_5.0.2_all.deb) ...  
Unpacking replacement software-center ...  
Preparing to replace software-properties-common 0.81.13.1 (using .../software-properties-common_0.81.13.1_all.deb) ...  
Unpacking replacement software-properties-common ...  
Preparing to replace software-properties-gtk 0.81.13.1 (using .../software-properties-gtk_0.81.13.1_all.deb) ...  
Unpacking replacement software-properties-gtk ...  
Processing triggers for desktop-file-utils ...  
Processing triggers for gnome-menus ...  
Processing triggers for bamfdaemon ...  
Rebuilding /usr/share/applications/bamf.index...  
Processing triggers for hicolor-icon-theme ...  
Processing triggers for man-db ...  
Processing triggers for shared-mime-info ...  
Unknown media type in type 'all/all'  
Unknown media type in type 'all/allfiles'  
Unknown media type in type 'uri/mms'  
Unknown media type in type 'uri/mmst'  
Unknown media type in type 'uri/mmsu'  
Unknown media type in type 'uri/pnm'  
Unknown media type in type 'uri/rtspt'  
Unknown media type in type 'uri/rtspu'  
Unknown media type in type 'interface/x-winamp-skin'  
Setting up software-center (5.0.2) ...  
Traceback (most recent call last):  
  File "/usr/sbin/update-software-center", line 38, in <module>  
    from softwarecenter.db.update import rebuild_database  
  File "/usr/share/software-center/softwarecenter/db/update.py", line 59, in <module>  
    from softwarecenter.db.database import parse_axi_values_file  
  File "/usr/share/software-center/softwarecenter/db/database.py", line 26, in <module>  
    from softwarecenter.db.application import Application  
  File "/usr/share/software-center/softwarecenter/db/application.py", line 25, in  <module>  
    from softwarecenter.backend.channel import is_channel_available  
  File "/usr/share/software-center/softwarecenter/backend/channel.py", line 25, in <module>  
    from softwarecenter.distro import get_distro  
  File "/usr/share/software-center/softwarecenter/distro/__init__.py", line 165, in <module>  
    distro_instance=_get_distro()  
  File "/usr/share/software-center/softwarecenter/distro/__init__.py", line 148, in _get_distro  
    module =  __import__(distro_id, globals(), locals(), [], -1)  
ImportError: No module named LinuxMint  
Setting up software-properties-common (0.81.13.1) ...  
Setting up software-properties-gtk (0.81.13.1) ...  
$

Is there a way to fix this problem without having to reinstall Ubuntu 11.10??

thanks in advance tinuz