Repair Windows media player 10

I installed windows media player 11 on my friend computer but decided to return to version 10 but now I am getting error window saying the file wmplayer.exe has a version number of 11 while version 10 was expected, is not properly installed and should be reinstalled. When I try to reinstall version 10 I am not allowed because I get that I already have the latest version installed. I reinstalled version 11 and tried as instructed on this link http://www.microsoft.com/windows/windowsmedia/player/11/readme.aspx but still media player 10 is not working. Does a System Repair Installation solve this problem as my last resort

 

Try uninstalling and reinstalling WMP 10: Control Panel>Add or Remove Programs, in the left-hand pane click on "Add/Remove Windows Components." Scroll down to Windows Media Player and uncheck it, click the Next button.

Step through the wizard to uninstall WMP. Then go back and recheck it, click "Next" and step through the wizard again to reinstall it.

 

followed your instructions but still with no success. I will try system restore and if still not succesful I try a System repair installation

 

After several attempts, trying to rollback media player 11 since even this was unable to play as well, I tried and finaly successfully managed to reinstall media MP 11 and is working fine