Enable ping response in Win7

Control Panel --> System and security --> Windows Firewall --> Advanced settings --> Inbound rules --> New rule --> custom rule

in Protocol and ports: Protocol: ICMPv4 
on the same panel go to customize, choose "Specific ICMP types", check the box "echo request"

Reference link
http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/how-to-enable-ping-response-in-windows-7/5aff5f8d-f138-4c9a-8646-5b3a99f1cae6