Oracle Database Discussions

Hi I have a little problem, the first time I have created my database with emca, I could access http://localhost:5500/em to the oracle enteroprise manager. But since I have retsarted my computer I can't access it no more and I need to use it to unlock some accounts. Here is the content of portlist.ini

iSQL*Plus HTTP port number =5560
Enterprise Manager Console HTTP Port (test) = 1158
Enterprise Manager Agent Port (test) = 3938
Enterprise Manager Console HTTP Port (chucky) = 5500
Enterprise Manager Agent Port (chucky) = 1830

As I understand oracle should make a listen for the database chucky on port 5500 and 1830. But I get a connection refused and it is not listening on thiese ports so I believe this service is not started.
Is there a script to start the oracle enterprise manager?
How can I troubleshoot this?
why didi it work the first time and no more?

Thanks for your help