You cannot log in because the service is stopped.

It won't start because of the corruption error you found in the event viewer.

Go to the Log directory of SQL Server and open the ERRORLOG files. The most recent one is ERRORLOG and then you should have some more ERRORLOG.1, ERRORLOG.2... files (up to 6 by default). One of these should contain the original error, if you didn't attempt to start SQL Server too many times.

If it is data corruption in master, you should try to restore from a backup.