If it's a DVAR/Infection all you need to do is exit MW2 then go back onto MW2 and it will be gone.

Delete the patch and Re-Install it or go to the in Game setting and turn the Brightness up

You did make sure your eyes were open when you were experiencing said "black screen" didn't you?

And another thing to check is that the TV is definitely plugged in, some infections unplug the TV. If I had a pound for everytime my TV was unplugged because of an infection I'd have enough money to pay attention to the original question.

Check the TV settings with Alt+f4

You mean u got black screen on in game? If yes go to options and go brightness and put it normal . Should work.