here is the solution:
step 1:
open folder : C:\WINDOWS\Microsoft.Net\Framework\v3.0\Windows Communication Foundation
step 2:
run command:ServiceModelReg.exe /i /x
step3:
run command:%comspec% /k ""C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"" x86
step 4:
run command: aspnet_regiis.exe -i
and then the following message will print out on the screen:
Start installing ASP.NET (4.0.30319).
............
Finished installing ASP.NET (4.0.30319).
now you should access your WCF service hosted on IIS7.5