SQL Server sa login if not working

 ALTER LOGIN sa ENABLE ;

GO ALTER LOGIN sa WITH PASSWORD = 'FossTechnix@123'; GO

>Also you have to Open Sql server management studio

>right click on server and click on properties

>Click on security

>Click on (SQL server and windows authentication mode) and click on OK

(Please see below screenshot)

And restart sql services

https://www.fosstechnix.com/how-to-enable-sa-account-in-sql-server/