We have a site where one of our team of techies installed SQL Server 2012. They forgot to add our administrators group as sysadmins so only they can access SQL - everyone else gets "Access Denied"
How can we find out who installed SQL, or who is a SQL Administrator so we can ask them to correct their fault?
I have domain admin rights to the server.
Since you have admin rights to the server you can use the same procedure used to recover access when system administrators are locked out.
MSDN: Connect to SQL Server When System Administrators Are Locked Out