Had this problem where the sa account had been locked. It turns out there is a simple way to unlock it from the SQL Management Studio.
For unlocking SA, you have to connect as a machine administrator to the server. The machine administrators are by default granted access to SQL Server.
In the query Analyser, connected to Master DB send in the command
ALTER LOGIN sa WITH PASSWORD = '_password' UNLOCK
And it worked, afterwards our sa account was working again.
Thank this msdn thread for the original answer.
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/e3783055-09c3-458d-8cf0-602ad16cac6f/sa-account-locked-out?forum=sqlsecurity
