Microsoft have announced that they will be introducing a new "Sandbox" feature in April's Windows 10 feature update. This will enable users to fire up a copy of Windows inside Windows to try and run any file they're not sure about.
Previously, if you really needed to test a possibly dodgy file, you would have to install some sort of "virtual machine" program on your PC, and then get hold of a licenced copy of Windows to run on it. With this update, all you will need is to be running Windows 10 Pro or Enterprise (and have a reasonably modern PC that supports the technology to enable this to work).
If your machine does support this new feature, if you are sent a file you're unsure about, or want to perform any sort of operation that you're worried might affect your machine adversely, all you will need to do is just run this new Sandbox mode. This will bring up another copy of Windows in a window of its own that is entirely sectioned off from the main Windows installation on the machine. You can then just drag and drop files into this window, run them, see what happens, and then act accordingly. When you close the Window, that "sandbox" is destroyed. Therefore, if it is a dodgy file, no damage is done.