[ubuntu] How to restore a file to its previous location?

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http://ubuntuforums.org – Hello, I was exploring Ubuntu and I clicked on Dash. I searched for "Naut..." then I saw 2 applications their mames are "Home Folder" and "Files". Accidently, I transported Files to the Desktop. I've 2 questions which may be unimportant. Sorry for wasting your time. 1. Can someone tell me where were it to restore it? I don't want to put a system file on my desktop. 2. Is there anyway to restore a file to its previous location (I don't have a backup)? 3. This question's out of this topic. If I want to install a big program (game), should I install it at the OS part (Hardware)