If you are getting Microsoft SQL Server Error 18456 Login Failed for User sa error to connect with system admin (SA) Login.
Then you can apply below step to resolve this issue
Go to SQL Server Properties - Security - Server Authentication section- check Sql Server and Windows authentication mode
Then you can apply below step to resolve this issue
Go to SQL Server Properties - Security - Server Authentication section- check Sql Server and Windows authentication mode
After that restart SQL server services then it will work fine.