Should I let my friend know he is infected?

[Launcher]

Okay, I told him. I said that he should change his password and that he should scan his computer. He hasn't replied and I don't think he ever will. Some thanks I get, haha.

Well at least you let him know. Maybe he thought your email was a spam since there are a lot these day just saying YOU are infected blah blah and he may have just thought that is what it was.
Either way there is not much else you can do.
Unless he already had several other people tell him that he was infected and this was old news that he just doesn't care about being infected.