I had an issue with this when I started up my SharePoint 2013 VM. I couldn’t start the MSSqlserver due to a log on error.
I found these steps that seemed to fix the issue.
- 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”
If that doesn’t work try adding the account and password again.