SQL Server 2012 can't start because of a login failure

Question

I recently installed Microsoft SQL Server 2012 on a fresh Windows 7 installation, but whenever I want to run the server, I get the following error:

Error

Answer 1

One possibility is when installed sql server data tools Bi, while sql server was already set up.

Solution:- 1.Just Repair the sql server with the set up instance

if solution does not work , than its worth your time meddling with services.msc