Run the Flash Player Uninstaller as applicable for your machine(i.e.Windows or MAC) and remove flash player.
For MAC : http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.h tml
For Windows : http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows. html
Restart the machine.
Download and Re-install Flash Player.
Restart the browser and check.
You might also wanna check the below articles ::
Enabling Flash Player in Internet Explorer 9 : http://forums.adobe.com/thread/885448
ActiveX Filtering in Internet Explorer 9 : http://forums.adobe.com/thread/867968
Cheers!
Arpit
North America
Europe, Middle East and Africa
Asia Pacific