Question: Is yout wamp manager icon ( in the system tray ) GREEN? It should be. If not either Apache or Mysql has not started properly. Its usually Apache that is the problem.
If not GREEN { left click the wamp manager icon -> Apache -> Service -> Test Port 80 }
This loads a command window and prints a message telling you if anything is using TCP port 80 on your PC.
A number of apps will try to use port 80 quite legitimately, but they must be uninstalled or reconfigured as web servers always use port 80.
IIS - Uninstall it if you are not using it.
SKYPE - Reconfigure it to NOT use port 80.
Others - You will have to tell us what is using the port.