I haven't looked at the included log files, but often, upon restarting the system, prweb does not automatically restart. It sounds as if this is what happened. Go to the root page (which would be that portion of the URL that precedes the /prweb) and login as the Tomcat administrator; hopefully you know the login. You will get a page that shows all of the started aps. If prweb is not started, click on the "start" button. It usually takes a few minutes for it to start.
From the logs we can see that you are getting the below error:
Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
Could you please check the Tomcat's web.xml file for the port used and ensure no other services are using this. Also, ensure the database is running. Pega requires the database to be started and running first before it can boostrap.