The Following code the reasons for "Page Cannot Be Displayed"
1. The server is not properly not started check the startup.bat for windows startup.sh for linux
2. Check the Server.xml file for the port number if it is set to 8080 ...
3.Only for windows check that IIS server is running as system process or not if it is running as systems startsup then change the Tomcat Port to some other number basically 8080 port is default for the IIS web server on windows OS.
For further clarifications do write u r OS version Tomcat version
Regards
S.N.Satish Kumar