reset password for connecting to an existing farms in SBS2011

OS: SBS2011std SP1 inside: Sharepoint 2010 and Sql2008R2 and AD

I unplugged an existing farms. When I run wizard SharePoint to plug again, put current name server database, next it wants a password to an existing farms. I try everyone password like admin, etc, and I can not connect to my farms.

Can you help me?

Thx