1. Click on "my computer"
2. Now click on "local c:".....(or on whatever hard drive you have installed windows on that might not be assigned the letter "c".
3. Now check if you have folder called "windows.old" it should be below the "windows" folder.
If you have the the "windows.old" folder then you didnt really format the hard drive but just installed windows again. This will cause the windows folder to be renamed window.old so that this older windows install will not bootup yet it you can recover all your files, like documents, music, videos..etc, and then move it to the present windows installation and you are then free to delete it. However DO NOT delete anything until you are sure, if its not there obviously delete nothing.