To activate the hidden theme of the window 7, follow the steps as follows.
• Step 1: Open the Explorer (Windows + E) and go to C: Windowswinsxs
• Step 2: Enter *. theme into the search field. Alternately you can use the * sign on the number block.
• Step 3: You'll get the prompt Click me
• Step 4: Double-click the themes ZA, U.S., GB, CA, AU to install them.