In addition to the answer above, if you have the misery of forgetting the Sitecore password then this will save you:
UPDATE [aspnet_Membership] SET [Password]='qOvF8m8F2IcWMvfOBjJYHmfLABc=',
[PasswordSalt]='OM5gu45RQuJ76itRvkSPFw==',
[IsApproved] = '1', [IsLockedOut] = '0'
WHERE UserId IN (SELECT UserId FROM dbo.aspnet_Users WHERE UserName = 'sitecore\Admin')
It resets the password to the classic 'b'.
