If you have a WCF Service Library Project in VS 2012 and after you wrote some functional code and then you decided to change the project from a WCF Service Library that doesn't contain web configurations and can't be hosted in the IIS to a WCF service application that is hosted in IIS, this blog post will tell you how to do it in details.
The WCF service library doesn't contains the Web Configuration Tab when you open the project configuration (By right click on the project --> Project Properties) and it has only app.config file and not web.config file because it is not suppose to be hosted in the IIS.
To change your WCF service library to WCF Service Application:
1) Right click on the wcf project and click on unload project.
2) After the project is being unloaded, right click on the wcf project and click edit the project configuration file ".csproj".
3) Look for the following attribute
Change the project type to the following:
4) Reload the project.
5) Open the project configuration, you will be able to see the web tab to configure the wcf service.
6) Add web.cofig file to your project.
7) Copy any necassary keys from the app.config to the web.config.
8) Rename or delete the app.config file.
9) Make sure that you have correct port and end point configuration in the web.config.
10) Clean and Build your project. At this point the project is build with no errors.
After you run the project you will see that there is no .svc file that is the service application file used to call the WCF. But you need to have one in your project.
11) First Rename your Service.cs and IService.cs.
12) Add new WCF Service svc to your project and name it as you like.
13) Copy the code you have in the Service Class and the interface to the newly created service.
14) Compile the project.
15) Run the WCF Service application and now your WCF can be accessed through the web.
This works with VS 2012 project templates with Update 2 as well.
Hope this helps.