The first thing you should do is check the log files for the PPM server to see if it has started properly. If you haven't changed any logging settings, the log should print out to the Cygwin window that you started PPM with. If you have closed that Cygwin window, that may be part of the problem. On Windows servers, you really need to use the services control panel to start and stop PPM. If you start PPM in the Cygwin window, once you close the Cygwin window, all processes that it started are terminated, including PPM. The installation should have created a service entry called 'HP PPM <servername>' that you can start and stop through the Services control panel.
But getting back to the log file, that will be in <PPM_HOME>\server\<servername>\log and will be called serverLog.txt. Look through that file, specifically at the end of the file, to see what may or may not be happening with your PPM instance.