Any exceptions or warnings in $JBOSS_HOME/standalone/log/server.log?
Did you change standalone.xml or whatever config file you're using?
Port should usually be 9990. Try if you can access http://localhost:9990/console/ ?
Check your server.log if you can find the line:
Admin console listening on http
actually the port 9990 was already used. I changed it in the file : $JBOSS_HOME/standalone/configuration/standalone.xml to 9991,
and it solves the problem.