Mondern warfare 2 online not working

i have a good connection but my nat type is strict, so it doesnt let me play, but one time it worked for some reason!!! will i have any hope for it to work again? if not any way to fix this?

I know that there is a certain way to fix the NAT. I think you'll have to check out the MW2 forums about it. I know that they have a fix on that or how to open up your NAT.