Well, first you have to know which one you have. Did you ever install a 3rd party Anti-virus (Avast, AVG, McAfee, Norton ring any bells?). If not, then you have Windows Defender if you're using Windows (and I highly recommend looking for a better anti-virus). If you're not using windows, I can't help beyond this.
Once you've got that, search your computer for that anti-virus program and run the executable. In the UI that comes up, you should be able to find your way to something along the lines of "Quarantine", "Sandbox", or "Virus Chest". That's where the .exe has been moved and waiting for you to perform some sort of action on it, one of which is usually "Restore and Add Exception"