Whoa everyone, let's calm down here.
OP: When you say you can't stream anymore, what do you mean by that? What happens when you try to stream? Do you get an error message?
A log would help a lot. If you can't post it as an attachment, then post it to
http://pastebin.com and then link to it here.
I can assure you that TwitchTest did not "cause" you to not be able to stream, though. It is, indeed, a reputable program, created by R1CH, one of the OBS developers. If you're worried about entering your stream key, you can feel free to reset it. However, just because a program needs your stream key doesn't mean it's an untrustworthy program. OBS needs your stream key as well, after all.
So since TwitchTest did not cause the problem, let's find out what did. I hope can do that without assuming the worst about each other.