The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020)

This problem is caused when another application runs on default port i.e. :80.

Most probably this issue occur because of Skype.

You can find the application which is running on that particular port by following command:

Open command prompt as administrator mode and type following command:

netstat -ano

This command list the process running on particular port. Please close that application and start your website from iis manager.

Now, You can able to access it as previously.