Windows 7 Ultimate
I used to have Git Shell installed. The icon is grey with a cat face. It was either installed by the Git or by GitHub for Windows.
Somehow
I found out that the answer that you specifically wanted involves a combination of the previous answers: 1. Running the Git Shell via the command line (Since you lost the shortcut)
C:\Users\Username\AppData\Local\GitHub\GitHub.appref-ms --open-shell
2. Once youre in the Git Shell run the command in the previous answer
github --reinstall-shortcuts
You'll find the Git Shell with the grey cat icon that originally came with the GitHub setup in the desktop.