Maybe the question has been understood badly by the previous posters.

I read "You had a problem with SQL Server and needed to restart the instance. After the restart, you want to check for problems in the error log"

For me , the check of the problem can be found only in the error log in use when the problem occured , that's to say not errorlog but errorlog.1

I recognize that , as DBA , I would have a look on both error logs to be sure that the problem is not repeating.