Forgot SQL Password
So you are here because you for got your mater password or didn’t enable SQL authentication and create an SA password on setup and your windows authentication is failing… Well the good news is this should help you change the password.
Below are the steps for SQL 2008 (the same can be applied to 2005, change the paths accordingly)
Follow the steps below to rebuild the Master Database.
1. From a command prompt window change to the following directory:
"C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Release"
2. Next paste the following into the command prompt window and press “Enter”:
Setup.Exe /Action=RebuildDatabase /InstanceName=MSSQLSERVER /SqlSysAdminAccounts=domain\UserName
The instance name will be MSSQLSERVER unless you are using a named instance and in that case change MSSQLSERVER to your instance name and the SqlSysAdminAccounts will be an account with SysAdmin (Be sure to change the domain\username details) rights then and press “Enter” again.
That should do it!