Malicious .ISO file

I have Norton 360 on Windows 10 PC.  A malicious .iso disk image file is executing on my desktop .  I shut down the computer and unplugged it from the internet. What should I do next?

@CassandraN Behler Its be a very long time since the last post so I am following up to see what your progress has been, can we assist further?

SA

Hello Cassandra. For the time being leave the computer powered down and do not use it. So that we can get a better understanding of things, please answer the following questions if you'd be so kind:

- Can you tell us the image name that is executing? Did you happen to get any screenshots to share before shutting down? Any alerts from Norton the files are malicious?

- Have you opened any messages that have attachments to them recently? 

- What operating system is installed? IE: Windows 10 your post states, is it Home/ Pro and what version. Is it fully updated?

- Have you or anyone with access to the desktop downloaded ANY ISO images recently? If so what was the image for? Where was the image downloaded from? 

- Any other information will be helpful but please DO NOT post anything that personally identifiable. 

SA