Slava Murygin has ten Powershell scripts to help administer a SQL Server instance:
Script #5. Read SQL Server Error Log file.
That is extremely important troubleshooting script. When you start/restart the SQL Server service and it does not come up, you can run this script to see what was going on during the SQL Server startup and what was the problem (just note that value of “$SQLInstancePath” must be pre-set by previous script):
Click through for all of the scripts.