Lost Microsoft SQL Express password/user

On default, Mirasys VMS Complete package installs VMS with Microsoft SQL Express.
The installer adds this Windows user who is installing VMS to SQL SuperAdmin user.
If you have lost this user or password, here are some tips on restoring access to SQL Express.

Enable Mixed Mode Authentication for SQL Server

There are different ways to enable Mixed Mode Authentication

Way 1

Enable SQL Server Mixed Mode Authentication by changing instance properties

Open Microsoft SQL Server Management Studio
Click Properties on SQL Server
Go to Security
Change Server authentication mode to SQL Server and Windows Authentication mode
After this, you get a notification that you need to restart SQL Server to change these settings active
- This can be done on Windows Services

Way 2

Enable Mixed Mode Authentication in Registry Editor

Open Registry Editor
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL12.SQLEXPRESS\MSSQLServer
- MSSQL12.SQLEXPRESS depends on what is your installed version
Change the value of LoginMode from 1 to 2
Close Registry Editor
Restart SQL Server to change these settings active
- This can be done on Windows Services

Recover a lost SuperAdmin (SA) password

To start recovering SuperAdmin (SA) password, there is need to change how SQL Server authenticate users

Stop all Mirasys VMS servicers
- WDServer
- DVRServer
- SMServer
Open SQL Server Configurator Manager
Select SQL Server Services
Open with right-click SQL Server Properties
Add under Startup Parameters parameter -m
Apply settings and click the OK button for the warning message window
- Restart SQL Server service
Open Command Prompt as Administrator mode
Type there command SQLCMD -S localhost
This open console to SQL Server
First, you need to enable a user with the command

CODE

ALTER LOGIN sa enable
GO

Then you need to create a new user with sysadmin user rights

CODE

CREATE LOGIN NewSA WITH PASSWORD = 'Password@1234';
ALTER SERVER ROLE sysadmin ADD MEMBER NewSA
GO

If you want to use a Windows account to log in, you can add this using these commands

CODE

CREATE LOGIN [ComputerName\username] FROM WINDOWS
GO
ALTER SERVER ROLE sysadmin ADD MEMBER [ComputerName\username]
GO

When changes are done, remove SQL Server startup parameter and restart SQL Server

After these changes, you can log in to SQL Server using SQL Server Management Studio with NewSA user or Windows user to SQL Server and change the SuperAdmin (SA) user password and remove unnecessary users from SQL Server.

Sources
4 Ways to Enable Mixed Mode Authentication for SQL Server (isunshare.com)
Recover a lost SA password (sqlshack.com)