osql –E– Login with your Win­dows credential

to change your authen­ti­ca­tion mode to Mixed Mode (mean­ing you can use both local pass­word such as sa, and Win­dows Cre­den­tials), change…

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\MSSQLServer\LoginMode from 1 (default) to 2(mixed).

Now that you have mixed, mode you can change the sa password..

osql –E

sp_password NULL,”<new-password>”,sa

go