Welcome to PressF1.
Go into add/remove programs in the control panel. Remove anything 'flash player' ish thats under either Macromedia or Adobe. Go to www.adobe.com and download the latest flash player.
If you want to reinstall Macromedia Player, go here. Probably be better to leave it off, it normally only gets installed by apps/websites that need to run graphic content that were made in Flash Player.