ActiveX / Flash / Moving pictures

I have a Vaio laptop with Vista.
About 4 days ago I lost any moving pictures on my laptop - obviously don't know the technical terms for this!
I can't watch any films on You Tube, and email attachements that are moving. I can't see any advertisements or websites that require Flash.

I have tried to download Flash and ActiveX but nothing happens. All my add ons are enabled.

I haven't downloaded any funny software that should affect these things but i didn install and uninstall DiveX a couple of weeks ago

I don't have a clue what's happened - can anyone help??