Why flash ,activex, not appearing in add ons

i have iexplorer 8 ,i have downloaded flash 10 several times ,but still browser cant play youtube videos and other flash content , it is not appearing in manage add ons ,neither is activex and shockwave appearing , it is downloading but not playing ..

note: i accidently removed flash ,active x ,from control panel ,but now have downloaded again but...??

please give solutions.:)

please answer it quick ,i am running out of time, actually the problem is that the browser is not playing youtube videos ,and flash content of sites ,i downloaded latest flash player but still cannot...please give opinion !

This could be the result of either of the following problems:

You downloaded Flash player for firefox instead of internet explorer.

You have the flash player activeX disabled in "Manage Addons" option in IE

Registry entries for Flash player are corrupt. Solution: Scan registry with a good registry cleaner.

Your IE8 installation is corrupt. Solution: Re-install IE

Your IE security settings are too high. Reduce them a bit. ('Medium high' or just 'Medium')

You have disabled javascript somehow in IE (if you get a message like javascript disabled - when playing youtube videos)