First Login as Windows Authentication
After open SQL Server double click on Security -> Logins -> Right click on sa user and open properties as below
After open SQL Server double click on Security -> Logins -> Right click on sa user and open properties as below
By default property of SA user as Below
Unclick Enforce Password policy and Enforce Password Expiration and enter any password which you wants to give (I given "sa" password for demonstrate purpose)
Now just disconnect or reopen the SQL SERVER and select SQL SERVER Authentication and user name will be :: "sa" and password is :: "sa" because i given the "sa" password for showing you all guys.
Its done Enjoy !!!!! :)
