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

The answer to this may be identical to the problem with full blown SQL Server (NTService\MSSQLSERVER) and this is to reset the password. The ironic thing is, there is no password.

Steps are:

• Right click on the Service in the Services mmc
• Click Properties
• Click on the Log On tab
• The password fields will appear to have entries in them...
• Blank out both Password fields
• Click "OK"

This should re-grant access to the service and it should start up again. Weird?

NOTE: if the problem comes back after a few hours or days, then you probably have a group policy which is overriding your settings and it's coming and taking the right away again.

This happened to me. A policy on the domain was taking away the SQL Server user account's "Log on as a service" rights. You can work around this using JLo's solution, but does not address the group policy problem specifically and it will return next time the group policies are refreshed on the machine.

The specific policy causing the issue for me was: Under, Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> User Rights Assignments: Log on as a service

You can see which policies are being applied to your machine by running the command "rsop" from the command line. Follow the path to the policy listed above and you will see its current value as well as which GPO set the value.