Re enable Windows Authetication in SQL Server My old employee has disabled Windows Authentication in our server. Now I'm not able to access the SQL Server even though I have Administrator access to the server. I need to reset the sa password.

I tried logging in using single user mode as Remus described but I get the following error:


  Login failed for user 'SERVER\Administrator'. 
  Reason: The account is disabled. (Microsoft SQL Server, Error: 18470)
Follow the steps in:

Connect to SQL Server When System Administrators Are Locked Out.

Briefly:


Start server with the -m switch
Connect as  a local administrator
Enable the sa account (and reset its password if necessary)
Restart server normally