You have to mean "an" account, most probably that account is frozen for good.

I think you should tell your friend what happened and ask him/her to check his/her email. Even if you're betting on it being a temporary ban, what if your friend committed a 2nd offence and then he/she finds out that you actually did something illegal with his/her account then? Honesty is the best policy, just come clean and face the music because YOU are to be blamed for this, there's no other way around it.

Good luck! And kudos to Blizzard for such a fast and effective response!

Blizzard wasn't this serious in the begining. I remember in my previous server, we had lotsssss of chinese farmers and I know a lot of them by names. One day all of them just disappeared, not a SINGLE one of them ever came online again. I knew one of them pretty well, he owns a company in China where he would employ people (usually students) to farm for gold in shifts. He owns about 10 accounts and he forwarded the emails that Blizzard sent to him. At the end of the emails Blizzard said "Under no circumstances will this account be reactivated". So yeah, they are DEAD serious. Of course after that ban, prices major mana pots and travellers backpacks went up sky high (