You are posting in a wrong and very old thread.

Ask your friend to appeal by him/herself (may be there will be questions about account history which only be answered by account owner.)

Do followings:
1. Create a temporary account like e.g. bney_ban_appeal or bney1
2. Create a NEW THREAD in meta section https://bitcointalk.org/index.php?board=24.0
3. Request for ban appeal or give a solid reason why moderators should unban you or give you a chance if it was any violation of any forum rules
4. Remember don't post any where else on the forum, your temporary account is only for appeal to unban your original account.