When trying to navigate to a file with the extension .svc when using IIS7 or IIS7.5 (that is in Windows Vista and Windows 2008/ 2008R2), you may get an error like this:
Server Error in Application "Default Web Site/ServiceName"
HTTP Error 404.3 - Not Found
To Resolve this:
1) Select "run" from the Start menu
2) Type "cmd" and click OK
3) Type "cd c:\windows\Microsoft.Net\Framework\v3.0\Windows Communication Foundation\" and press Enter.
4) Type "ServiceModelReg -i" and press Enter
5) WCF will now be installed.
6) And if already installed then type "ServiceModelReg -r" and press Enter