Grant administrative access to MS SQL Server

Due to some configuration errors SQL server can lose access to the console. In this article I will describe the steps to provide access to the server for the local administrator SQL

Open services.msc
Stop "SQL Server (MSSQLSERVER)" (or other instance name)
Determinete path where sqlservr.exe e.g. "C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Binn\sqlservr.exe"

Open cmd.exe

Run SQL with minimum configuration e.g. "C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Binn\sqlservr.exe" -f

Open cmd.exe
Run sqlcmd.exe and this command

CREATE LOGIN [PCNAME\admin] FROM WINDOWS
GO
ALTER SERVER ROLE [sysadmin] ADD MEMBER [PCNAME\admin]
GO

 Press CRTL-C in cmd running sqlservr.exe -f, press "Y"

Open services.msc

Start "SQL Server (MSSQLSERVER)" (or other instance name)